Comment by srean

The story of the third paper:

Bose had sent Einstein a follow-up work after his second submission to him on thermal equilibrium of matter and radiation. The second paper had been published but along with Einstein's takedown. This seems to have mortified Bose. He was expecting a personal review and rejection from publication of a paper that has been judged faulty. The third paper, presumably addressed the objections.

Einstein, however, remained unconvinced and did not arrange for its publication.

This third submission is lost.