Mo. Rev. Stat. § 490.520: Proof of partnership.

Whenever it becomes necessary in any suit to prove the existence of a partnership, an affidavit of a competent witness, setting forth the names and places of residence of all the partners, the name of the firm, the general nature of the business and where transacted, and the time of the commencement or existence of such partnership, shall be prima facie evidence of the facts therein stated.