Nathan Crilly has written a lot about the phenomena of design fixation that is discussed in the podcast. Two very recent publications of his, in volume 64 of the journal Design Studies, are a good place to start. One is of case studies of creative discovery, and the other summarises the theory of design fixation to date. The key early work he refers to, that first identified the design fixation phenomena in 1991, is by David Jansson and Stephen Smith in Volume 12 of Design Studies.