These lectures at the University of Madras in 1935 by the archaeologist K. N. Dikshit is a little known but well-written and surprisingly relevant summary of what was known about the ancient Indus civilization after the first 14 years of excavations. >
Books on the evolution or change in popular theory of the field and study of the ancient Indus Valley and Harappan people, their culture, architecture, artifacts, and language as well as the change of the locations and sites themselves.