McClure, M. T. (1923). Solving a simple problem. In M. T. McClure, How to think in business (pp. 11-15). New York, NY, US: McGraw-Hill Book Company.
http://dx.doi.org/10.1037/10968-001
As a general method of procedure we shall begin with what is simple and advance gradually to what is more difficult. In accordance with the view that the thinking process is a problem-solving process, we begin with the example of a problem the solution of which involves a simple case of practical deliberation. (PsycINFO Database Record (c) 2016 APA, all rights reserved)