"Loud & Clear" by Robert J Serling provides a superb narrative of the accidents and subsequent investigations noted above by rog747 (the book also covers the Electra)
Although the 727 was fully exonerated, training reforms associated with handling the jet during the approach phase were introduced by all operating airlines
Another great 727 source is the DP Davies interviews which can be found elsewhere on this forum and in particular his insistence on the installation of stick pushers on the Dan Air 727's thanks to his vast experience with the deep stall problems which surrounded the early T-tail jets