Cita APA (7a ed.)

Helpman, E., & Krugman, P. R. (1993). Market structure and foreign trade: Increasing returns, imperfect competitition and the international economy. MIT.

Cita Chicago Style (17a ed.)

Helpman, Elhanan, y Paul R. Krugman. Market Structure and Foreign Trade: Increasing Returns, Imperfect Competitition and the International Economy. Cambridge (Massachusetts) [etc.]: MIT, 1993.

Cita MLA (9a ed.)

Helpman, Elhanan, y Paul R. Krugman. Market Structure and Foreign Trade: Increasing Returns, Imperfect Competitition and the International Economy. MIT, 1993.