In an *859action to recover the value of goods sold and delivered, and on the guarantee of payment therefor, plaintiff appeals from so much of an order of the Supreme Court, Queens County (Lerner, J.), dated May 26, 1981, as denied its motion for summary judgment. Order reversed insofar as appealed from, on the law, with one bill of $50 costs and disbursements, and plaintiff’s motion granted. Defendants failed to oppose the motion for summary judgment with evidence sufficient to raise a triable issue of fact. Bald conclusory assertions are not enough to defeat a motion for summary judgment even if believable; it is essential that defendants disclose their proof in evidentiary form (Mallad Constr. Corp. v County Fed. Sav. & Loan Assn., 32 NY2d 285). Additionally, affidavits submitted are probative of the facts contained therein only to the extent that the affiant has personal knowledge of those facts (Zuckerman v City of New York, 49 NY2d 557). Defendants’ opposing papers consisted largely of nonprobative allegations and irrelevant, frivolous issues. They failed to present any proof in evidentiary form showing nondelivery of the merchandise. In view of plaintiff’s receipts signed by defendant Allstates Food Corp.’s employees, accompanied by an affidavit of Allstates’ former marketing director and manager of operations stating that to his personal knowledge those signatures were genuine and authorized, defendants’ opposition to the motion must fail. Damiani, J. P., Lazer, Mangano and Gibbons, JJ., concur.