Franco Modigliani and Merton H. Miller. "The cost of capital, corporation finance and the theory of investment." The American economic review (1958): 261-297.
Famous Franco Modigliani Quotes
Conversations with Economists (1983)
Franco Modigliani (2001) Adventures of an economist, p. 41.
though it might conceivably be in some different ones!
Conversations with Economists (1983)
Franco Modigliani, " Life Cycle, Individual Thrift and the Wealth of Nations http://piketty.pse.ens.fr/fichiers/enseig/ecoineg/EcoIneg_fichiers/ModiglianiNobelLecture1985(AER1986).pdf" Lecture to the memory of Alfred Nobel, December 9, 1985, in: Nobel Lectures, Economics 1981-1990, Editor Karl-Göran Mäler, World Scientific Publishing Co., Singapore, 1992.