The notion of design as a "way of thinking" in the sciences can be traced to Herbert A. Simon's 1969 book "The Sciences of the Artificial", and in design engineering to Robert McKim's 1973 book "Experiences in Visual Thinking". Bryan Lawson's 1980 book "How Designers Think", primarily addressing design in architecture, began a process of generalising the concept of design thinking. A 1982 article by Nigel Cross, "Designerly Ways of Knowing", established some of the intrinsic qualities and abilities of design thinking that also made it relevant in general education and thus for wider audiences. Peter Rowe's 1987 book "Design Thinking", which described methods and approaches used by architects and urban planners, was a significant early usage of the term in the design research literature. An international series of research symposia in design thinking began at Delft University of Technology in 1991.