This collection includes many major titles in physics, mathematics, the philosophy of science, and literature. Monographs are primarily in English, French and German. In addition to the 20th century material, the collection features books from the 17th through 19th centuries. The collection includes audio tapes and transcripts of Dr. Mehra's interviews, conversations and discussions with over 75 major physicists, astrophysicists and cosmologists, as well as tapes of historic lecture programs. In addition to published works, the collection holds manuscript materials including correspondence with leading figures in science, mathematics, philosophy, and literature. The collection also features a large number of unpublished photographs of well-known scientists, philosophers and literati.