In 1977, the WTS published a 64-page booklet, "Jehovah's Witnesses and the Question of Blood". I examined the references given in that booklet and I found that the citations were less than precise. My study, which I completed in 1988, is still available.
At the time, I wrote to Ray Franz on the subject. His response to me is available at:
http://www.jwstudies.com/Letter_from_Ray_Franz.jpg
Doug