By Unidentified Author
By David Mitchell, Roy I. Brown
By robert thomson
By Paul H. Mussen
By John L. Phillips, Jr.
By Jean Piaget
By N/A
By Manfred F. DeMartino
By J. A. C. Brown
By Rudolf Allers'
By Walter J. Coville
By Norman L. Munn
By C. L. Wrenn
By Ida C. Ward
By Barbara M. H. Strang
By Simeon Potter
By Robert A. Hall Jr.
By R. L. Gregory
By Wolfgang Donsbach
By Henry James
By Chris Oxlade
By W. H. Newton
By Peter Hunt
By Duke-Elder
By Ragnar Granit
By Noel A. Brennan