Appellant was convicted of four counts of delivery of a controlled substance. These charges involve the delivery of heroin on July 14 and 21 and of cocaine on July 21 and 22. All in 1978. These deliveries were made to an informant who shall hereafter only be referred to as X throughout this opinion.
Appellant seeks reversal of these convictions for the reasons which are set out as follows:
1. “It was error for the trial court to admit the alleged to [sic] pre-recording of the transactions into evidence.”
*7532. “Appellant cannot be convicted of delivering cocaine unless the state has proved beyond a reasonable doubt that the substances tested by the state’s chemist are a form of cocaine that is either a derivative of coca leaves or a substance chemically equivalent or identical to such a derivative.”
3. “It was reversible error for the trial court to deny Appellant the use, at state expense, of a chemist and private investigator.”
4. “It was error to prohibit Appellant from inquiring of ... [State's expert witness] as to his academic training.”
5. “It was reversible error for the trial court to refuse to instruct the jury on Appellant’s theory of the case.”
We find no basis for reversal based upon these contentions.
Because of the posture of this case and the manner of its presentation, it appears proper to avoid needless repetition in our decision herein covering the points upon which the appellant seeks reversal to set out that error alone is not a basis for reversal but must affect substantial rights to be the basis therefor. Rule 49(a), W.R.Cr.P., and Rule 7.04, W.R.A.P. Additionally, it is the burden of appellant seeking reversal to demonstrate and establish the prejudice claimed. Nimmo v. State, Wyo., 603 P.2d 386, 393 (1979); Cosco v. State, Wyo., 503 P.2d 1403, 1406 (1972), certiorari denied 411 U.S. 971, 93 S.Ct. 2164, 36 L.Ed.2d 693 (1973); Kennedy v. State, Wyo., 559 P.2d 1014, 1018 (1977).
Generally, discretionary rulings of a trial judge are not reversible error unless a clear abuse of discretion is shown, Deeter v. State, Wyo., 500 P.2d 68, 71 (1972). A trial court is granted a reasonable discretion concerning the admissibility of evidence and error cannot be based thereon, absent an abuse of discretion. Reeder v. State, Wyo., 515 P.2d 969, 973 (1973), mandamus denied 419 U.S. 1018, 95 S.Ct. 509, 42 L.Ed.2d 303 (1974); Daellenbach v. State, Wyo., 562 P.2d 679, 682 (1977); Peterson v. State, Wyo., 586 P.2d 144, 154 (1978).
These last authorities are particularly applicable to the points numbered one and four.
Admission of the Tapes
The tapes to which objection is made were those containing conversations between Jackson and X, obtained by the use of a microphone taped to X’s body and also included some telephone conversations.
It is most difficult to determine just what is the basis of appellant’s complaint in connection with the reception of the tapes because of the manner in which it is presented. In his attack on their admission, he first asserts that they should be suppressed because they were taken in violation of §§ 37-12-112* and 37-12-125, W.S.1977. Additionally, he contends the recording of the telephone conversations violated the provisions of the Mountain States Telephone and Telegraph Company General Exchange Tariff, a copy of which does not appear to be in the record. Further, he claims that the transmissions of the body mike violated 47 U.S.C. 301 and 47 U.S.C. 153(b) and (c), because the parties did not possess a valid radio license. He, also, makes assertion that the tapes contained reference to possible criminal conduct which was not the subject of the matter before the court. He further asserts that the use of these tapes is a form of note-taking which violates the provisions of § 1-11-209, W.S.1977.
The position that these tapes were inadmissible because of the violation of the Wyoming statutes, the General Exchange Tariff of the telephone company, and the federal statutes, all before mentioned, is not buttressed by any cogent or applicable authority or argument.1
*754This court has many times repeated the necessity that an appellant support a claim of error by authority or cogent argument. Chernichwan v. State, Wyo., 594 P.2d 464, 470 (1979); Otte v. State, Wyo., 563 P.2d 1361, 1363 (1977); Scherling v. Kilgore, Wyo., 599 P.2d 1352, 1359 (1979).
The appellant’s statement that “possible criminal conduct,” is contained in the tapes and supported only by the assertion that this is error is totally insufficient. There is no attempt made to indicate the nature of the reference. We have no idea to what he is referring. This emphasizes the applicability of the rule of requiring cogent argument and applicable authorities. This is not presented in a manner which complies with the requirements of Rule 5.01, W.R.A.P., because it fails to include “a statement of the facts relevant to the issues presented by review, with appropriate page references to the record.” We cannot consider this.
The contention as to the violation of § 1-11-209, W.S.1977, is not only unsupported by authority but is more unique than logical and is not worthy of further mention.
He further asserts that these tapes are largely unintelligible and the matters thereon could not be understood. He nowhere states the nature of the omitted material or alleges that it was favorable to him. Without seeming to be facetious and without appearing to take this lightly, this writer finds it hard to believe that a juror might be prejudiced by what he did not hear.
It was proper to admit the tapes unless they were so unintelligible as to render them untrustworthy. The decision rests within the discretion of the trial judge. People v. Karrala, 35 Mich.App. 541, 192 N.W.2d 676, 679 (1971); see also 57 A.L.R.3d 746, note entitled “Admissibility of Inaudible Sound Recordings.”
The argument is made in appellant’s brief to sustain his contention of error that the admission of these tapes was governed by Rule 403, W.R.E. With this we have no argument but are unable to see how appellant found solace therein because this rule vests a discretion in the trial court to exclude relevant evidence, “if its probative value is substantially outweighed by the danger of unfair prejudice.” In Key v. State, Wyo., 616 P.2d 774, 775 (1980), this court recognized that Rule 403, supra, did not change the standard of review to be followed by this court and that rulings thereunder would not be reversed absent a clear showing of abuse of discretion. Appellant makes no such showing of abuse.
Cross-examination of Expert Witness
The trial court refused to allow defendant’s counsel to cross-examine the expert witness appearing for the State upon the grades which he received from the University of Wyoming where he was doing postgraduate work, the last of which grades were awarded to him some 12½ years before.
An expert is subject to a broad area of cross-examination to determine his expertise and questions which are fairly designed to test his expertise and to determine his qualifications and knowledge. Chrysler Corporation v. Todorovich, Wyo., 580 P.2d 1123, 1133 (1978). Even where this rule prevails, the area of cross-examination must remain within the discretion of the trial court. State v. Vennard, 159 Conn. 385, 270 A.2d 837, 844 (1970). The rule and reason therefor is set out in that case as follows:
“... One of the purposes of the cross-examination of an expert is to test his qualifications and credibility, and the trial court has broad discretion in determining whether a given question satisfies this purpose.... ” See also United States v. Wainright, 10 Cir., 413 F.2d 796, 801 (1969), certiorari denied 396 U.S. 1009, 90 S.Ct. 566, 24 L.Ed.2d 501, affirmed Wainright v. United States, 10 Cir., 448 F.2d 984; and 2 Jones on Evidence, § 14:30, p. 668 (6th Ed.).
Conceding arguendo that such evidence was relevant, the trial judge might have based his ruling upon Rule 403, supra. This evidence was so remote, it could be *755questionable and could tend to mislead and confuse a jury who might not well understand the grading system or its effect. This writer would personally question if the inquiry might be aimed at harassment of a witness rather than a search for qualifications.2
A trial court’s discretion in limiting cross-examination “will not be disturbed unless clearly prejudicial.” Nimmo v. State, supra, 603 P.2d at 393.
The writer must also observe that there is not a suggestion of any authority argued or cited that such an inquiry was proper or that to refuse it would be error. In absence of such citation of authority, we must assume appellant found no such authority. Nation v. State ex rel. Fire Fighters Local 279, I.A.P.F., Wyo., 518 P.2d 931, 933 (1974), with cited authorities. Appellant has in no manner sustained his burden of establishing error.
In pursuit of his contention that it was reversible error for the court to deny the appellant the use at State expense of a chemist and private investigator, appellant claims that this refusal violated various provisions of the Constitutions of this State and of the United States including the due process and equal protection provisions. We cannot reach these contentions. It would be entirely improper to explore the constitutionality of the court’s order because of the manner in which it is presented. Constitutional questions are too important to be answered unless fully and properly presented. Salt Creek Transportation Co. v. Public Service Commission, 37 Wyo. 488, 263 P. 621 (1928), cited with approval in Johnson v. Schrader, Wyo., 507 P.2d 814, 819 (1973). It is necessary that the constitutional questions be specifically phrased and completely argued before it would be proper for this court to pass upon them. Doe v. Burk, Wyo., 513 P.2d 643, 645 (1973), and cases cited. Appellant has failed to do this, and we will not explore this area of asserted constitutional violations.
Refusal to Appoint Investigator and Chemist at State’s Expense
The statutes upon which appellant relies in raising this claim are:
Ҥ 7-1-108. Definitions.
“(a) As used in this act:
* * * * * *
“(iv) ‘Needy person’ means a person who at the time his need is determined is unable to provide for the full payment of an attorney and all other necessary expenses of representation;”
Ҥ 7-1-110. Right to attorney; cost; other rights.
“(a) A needy person who is being detained by a law enforcement officer, or who is under formal charge of having committed, or is being detained under a conviction of, a serious crime, is entitled:
“(i) To be represented by an attorney to the same extent as a person having his own counsel is so entitled; and
“(ii) To be provided with the necessary services and facilities of representation (including investigation and other preparation).”
By virtue of the statutes there are two factual questions posed to the trial court for its disposal, i. e., is the defendant an indigent person under the statutes, and are the services necessary? These questions must rest in the sound discretion of the trial judge. State v. Knapp, 114 Ariz. 531, 562 P.2d 704, 713 (1977), certiorari denied 435 U.S. 908, 98 S.Ct. 1458, 55 L.Ed.2d 500 (1978); Collins v. State, 14 Md.App. 674, 288 A.2d 221, 224 (1972); State v. Campbell, 210 Kan. 265, 500 P.2d 21, 29 (1972); Brown v. District Court, 189 Colo. 469, 541 P.2d 1248 (1975).
*756A clear statement for the reasons that this be left to the court’s discretion appears in Magley v. State, 263 Ind. 618, 335 N.E.2d 811, 816 (1975), where the court said:
“. .. A wealthy person may hire any number of people to aid in his defense, needlessly, or on a whim, or foolishly, and the State does not control his expenditures. But, when the court is allocating state funds for the defense of a defendant, it is rational for the court to use discretion in granting or denying the defendant’s requests for additional personnel to aid him. Within the primary goal of the judicial process, which is due process of law for each defendant, the court may determine which expenses are probably needless, wasteful, or extravagant.”
The record shows that the appellant in this case was represented by retained counsel both at the trial and upon this appeal. A further examination of the record does not reveal any of the evidence produced at the hearing on these motions. There is nothing in this record which would support any conclusions that the appellant was “a needy person” or that services were necessary and proper. Appellant did, in an apparent attempt to make this a part of the record, file an instrument entitled “Statement of Evidence When Transcript Is Unavailable.” This was filed in reliance on Rule 4.03, W.R.A.P., but was stricken by this court because of the failure of appellant to comply with the conditions of this rule. Where, as here, the trial judge has not approved the statement of the record of evidence, this court cannot reach the issues. Petersen v. State, Wyo., 594 P.2d 978, 980 (1979). Absent evidence upon which this court could make any determination of this question it is apparent that appellant cannot predicate error upon this basis. There is nothing in the record upon which this court might make any disposition of this matter and it would be demonstrably improper and violative of basic and fundamental appellate rules to determine that the trial court had abused its discretion absent some evidence. This court said in Martinez v. State, Wyo., 611 P.2d 831, 838 (1980):
“A court does not abuse its discretion unless it acts in a manner which exceeds the bounds of reason under the circumstances. In determining whether there has been an abuse of discretion, the ultimate issue is whether or not the court could reasonably conclude as it did.”
This demonstrates the necessity of evidence to dispose of any contention that there has been any such abuse.
In his disposal thereof, the trial court by his letter held that the appellant had failed to prove the necessity or reasonableness of the expenses for the employment of the chemist or investigator.
Sufficiency of the Evidence
The appellant seeks to support his assertion of error that there was insufficient evidence to sustain these convictions because of the failure to prove that the material delivered was a controlled substance as defined by § 35-7-1016(a & b)(iv), W.S. 1977, which is as follows:
“(a) The controlled substances listed in this section are included in Schedule II. Schedule II shall consist of the drugs and other substances, by whatever official name, common or usual name, chemical name or brand name designated, listed in this section.
“(b) Substances, vegetable origin or chemical synthesis. — Unless specifically excepted or unless listed in another schedule, any of the following substances, except those narcotic drugs listed in other schedules, whether produced directly or indirectly by extraction from substances of vegetable origin, or independently by means of chemical synthesis, or by combination of extraction and chemical synthesis:
* * * * # *
“(iv) Coca leaves and any salt, compound, derivative, or preparation of coca leaves, and any salt, compound, derivative, or preparation thereof which is chemically equivalent or identical with any of these substances, but not including decocainized coca leaves or extractions which do not contain cocaine or ecgonine.”
*757In the course of his brief, defendant-appellant contends that D-cocaine is not covered thereby and inasmuch as no test was made to determine if this were L-coeaine or D-cocaine, there is no proof that this is a controlled substance under the statute.
This position cannot rest in either the law or the evidence. The State’s expert witness testified without equivocation that the material was cocaine. He made no test to determine if this were L-cocaine or D-eo-caine. He also testified that L-coeaine occurs naturally and that D-cocaine is a synthetic composition which is the equivalent of L-eocaine.
We must view the evidence in a light most favorable to the prosecution and resolve the evidence in favor of the State. Hovee v. State, Wyo., 596 P.2d 1127, 1133 (1979). The evidence was clearly sufficient to sustain a conviction. United States v. Wilburn, 10 Cir., 549 F.2d 734 (1977); People v. Harper, 193 Colo. 116, 562 P.2d 1112 (1977). We are unable to understand appellant's reliance upon United States v. Orzechowski, 7 Cir., 547 F.2d 978 (1977), certiorari denied 431 U.S. 906, 97 S.Ct. 1701, 52 L.Ed.2d 391 (1977), which is the only authority he cited. It is our view that if Orzechowski was the sole authority available, we would be forced to rule against appellant based thereon.
Refusal to Instruct
Appellant asserts that the district court was in error when it refused to give the following instruction:
“INSTRUCTION NO. 14
“It is the Defendant’s theory of the case that he was framed by ... [X]. [X’s] ... motive for this action was to buy his way out of two counts of assault with a deadly weapon, a gun, which carries a total penalty of up to twenty eight [sic] years at hard labor in the Wyoming State Penitentiary. [X] ... was advised by Judge Maier of this penalty on December 16, 1977.
“That on April 19, 1978, trial was set for [X] ... on June 5, 1978. That on May 23, 1978, Judge Johnson continued Mr. [X’s] ... trial because ‘there are on-going negotiations between the County Attorney’s office and the Defendant’.
“That in order to buy his way out of his criminal problems he framed a case against Wendell Jackson.”
The trial court committed no error in refusing to give this instruction. It is well-established that the defendant does have a right to an instruction upon the theory of his case if there is competent evidence. Blakely v. State, Wyo., 474 P.2d 127, 129 (1970). Absent competent evidence to sustain such a theory, defendant is not entitled to such an instruction. Goodman v. State, Wyo., 573 P.2d 400, 410 (1977), and authorities cited therein. We find no competent evidence upon which such instruction could be based. The obvious purpose of this instruction was to destroy the credibility of witness X and not to present the theory of defendant’s case.
The trial court did give a cautionary instruction 3 covering the credibility of a witness who testifies under a grant of immunity and which appears to have been offered by the defendant. It covers the testimony of a witness given under a grant of immunity. This instruction taken along with the general instruction to the jury, as to the effect of interest or motive, more than adequately advised the jury of the manner in which this testimony should be considered.
*758The cross-examination of X revealed the fact that immunity had been granted by the State. Argument to the jury was also made along these lines. When such facts are clearly before the jury, this court has suggested that it is not error to refuse to give a cautionary instruction of the nature which was here given. Channel v. State, Wyo., 592 P.2d 1145, 1151-1152 (1979); and Oldham v. State, Wyo., 534 P.2d 107, 109-110 (1975).
The court does not discuss other possible objections to the propriety of the proffered instruction because it was not necessary for the disposal hereof.
From what has been said herein, the judgment must be affirmed.
Affirmed.
Apparently appellant intended to refer to § 37-12-122, W.S.1977.
. In Todisco v. United States, 9 Cir., 298 F.2d 208, 211 (1961), the Court specifically refused to pass upon the question of whether there was a violation of 47 U.S.C. 301 and 47 U.S.C. 153(b & c) in making such tapes, but the Court specifically held that tapes so taken are admissible.
. The trial judge, in exercising his discretion, may well have considered that only one of the failing grades involved as shown in the transcript and upon which the defendant’s offer was based involved a chemistry course and the remainder were in other areas. The court was justified in believing that such questions couid not be fairly designed to test the witness’ expertise.
. “Instruction No. 14b
“One who testifies under a grant of immunity with a promise from the government that he will not be prosecuted is a competent witness. His testimony may be received in evidence and considered by the jury even though not corroborated or supported by other evidence.
“Such testimony, however, should be examined by you with greater care than the testimony of an ordinary witness. You should consider whether the testimony may be colored in such a way as to further the witness’s own interest, for a witness who realizes that he may procure his own freedom by incriminating another has motive [to] falsify. After such consideration, you may give the testimony of the immunized witness such weight as you feel it deserve [sic]”.