As a complement to more scholarly references, you might enjoy this video recording of a delightful interview with Kirby. In the section labeled "The Torus Trick," he gives a description ofdescribes the process which brought him to discover the trick, which I found enlightening both mathematically as well asand historically (thoughinteresting, though it's a bit brief). Some of the surrounding sections of the video contain further interesting information about the state of topology at the time.