Great text about the history of design research (by Nigel Cross)

Nigel Cross is one of the most influential scholars in the study of design as a process. He has made seminal contributions to the field and is probably most recognized for his notion of "designerly ways distinct human activity with its own forms of cognition, epistemology, methodology, and practice.
of knowing" which positions designing as a

Cross just published a new article "Developing design as a discipline" where he tells his own story of his life as a researcher. By doing that he also lays out the core of what design research has been doing in this area since the 60s.

I highly recommend this article.

Nigel Cross (2018) Developing design as a discipline, Journal of Engineering Design, 29:12, 691-708, DOI: 10.1080/09544828.2018.1537481