Perlman,Mark. (1977). The organization and retrieval of economic knowledge: Proceedings of a conference held by the international economic association at Keil, west Germany. Mac Millan.

Perlman,Mark. The Organization and Retrieval of Economic Knowledge: Proceedings of a Conference Held by the International Economic Association at Keil, West Germany. London: Mac Millan, 1977.

Perlman,Mark. The Organization and Retrieval of Economic Knowledge: Proceedings of a Conference Held by the International Economic Association at Keil, West Germany. Mac Millan, 1977.