Samuelson, P. A. (1958). Economics: An introductory analysis (4th.ed.). McGraw-Hill.

Samuelson, Paul A. Economics: An Introductory Analysis. 4th.ed. New York: McGraw-Hill, 1958.

Samuelson, Paul A. Economics: An Introductory Analysis. 4th.ed. McGraw-Hill, 1958.