J. Tinbergen, 1991. "Solving the Most Urgent Problems First", in Michael Szenberg (ed.) 1993, Eminent Economists: Their Life Philosophies, Cambridge University Press, p. 279 (cambridge.org).
Witold Gadomski, Rynek trzyma smycz [Gadomski o książce Belki] (The market holds the leash [Gadomski about Belka's book]). 11 June 2016. Rynek trzyma smycz. wyborcza.pl. Retrieved 26 June 2016.