Books by Helen L. Koch:
Books in the extended shelves:
![[X-Info]](https://onlinebooks.library.upenn.edu/infouc.gif)
Koch, Helen L. (Helen Lois), 1895-1977: The influence of mechanical guidance upon maze learning. (Princeton, N.J. : Psychological review company, [1923], 1923) (page images at HathiTrust)- Koch, Helen L. (Helen Lois), 1895-1977: A study of the test-performance of American, Mexican, and negro children. (Princeton, N.J. and Albany, N.Y. : The Psychological review company, [1926], 1926), also by Rietta Simmons (page images at HathiTrust)
Find more by Helen L. Koch at your library, or elsewhere.