From Economic Observer Online:
Guo Yukuan: Like many intellectuals of the time, you started as a railway engineer. How did you turn to study economics later on?
Mao Yushi: It was very late when I began to come into contact with economic theory. That said, since the early 1950s, I had already taken a deep interest in operations analysis. At that time, I had found an English book relating how the British used operations analysis to detect German submarines. From that book, I learned how to reduce coal-consumption and improve efficiency in the railway system. That was probably the first time I dealt with the economics.