He published several books and papers in German early on, among these the ‘Theory of Economic Development’ in 1912 and a revised edition in English in 1934, which present the main aspects of his theory. Among his most well-known later works are ‘Business Cycles’ in two volumes (1939), focusing on the tendency for innovations to ‘cluster’ in certain industries and time periods (and the derived effects on growth, e.g. so-called ‘long waves’ in the world economy), and ‘Capitalism, Socialism and Democracy’ (1942) which, among other things, discusses to what extent the capitalist system and its institutions can survive in the longer run.