Clapp, F. L. (1924). The number combinations, their relative difficulty and the frequency of their appearance in text-books; a brief summary of study no. 1.
Chicago Style (17th ed.) CitationClapp, Frank L. The Number Combinations, Their Relative Difficulty and the Frequency of Their Appearance in Text-books; a Brief Summary of Study No. 1. Madison, Wis, 1924.
MLA (8th ed.) CitationClapp, Frank L. The Number Combinations, Their Relative Difficulty and the Frequency of Their Appearance in Text-books; a Brief Summary of Study No. 1. 1924.
Warning: These citations may not always be 100% accurate.