What is the test for proving possession of boots?

Appellant contends that possession of these boots was proved only by his admission, which is insufficient under United States v. Smith, supra. To corroborate such an admission the Government need not produce independent evidence of every specific element of the crime. United States v. Smith, supra; Opper v. United States, 348 U.S. 84, 93, 75 S.Ct. 158, 99 L.Ed. 101 (1954). Rather, it need only produce substantial independent evidence which, together with the admission, establishes all elements of the crime and the admission's trustworthiness. Smith, supra; Opper, supra; United States v. Tourine, 428 F.2d 865, 867-868 (2d Cir. 1970), cert. denied, 400 U.S. 1020, 91 S.Ct. 581, 27 L.Ed.2d 631 (1971).⁵