Are you preparing for a like the ICAR JRF or NET, or are you just looking for a general reference for your classes?
The "best" version of this book is the most recent edition, as genetics is a field that changes rapidly. While a free PDF might help you in a pinch, the depth of B.D. Singh’s work is best realized through active note-taking and solving the back-of-chapter questions. principles of genetics by b d singh pdf free better best
However, "better" and "best" aren't just about finding a free download; they are about how you use the material to actually pass your exams. Why B.D. Singh is the "Best" Choice for Genetics Are you preparing for a like the ICAR