Mo. Rev. Stat. § 137.240: County commissions to furnish additional books when necessary.

In every county where, from the length of the assessment lists, it appears to the county commission of the county to be impossible or impracticable to include the lists in one book, the commission shall enter of record an order requiring the lists to be made in two or more volumes. Thereafter the assessment book or list shall be made in two or more separate volumes, numbered consecutively, and the affidavit required by section 137.245 shall be annexed to each volume, referring therein to the other volumes by inserting in lieu of the word "book", in the latter part of the affidavit, the words "volume and in volume ______ (herewith returned)".