APA

Oxfor University Press, . (1991). National health systems of the world. Estados Unidos: Oxford University Press.

Chicago

Oxfor University Press, . 1991. National health systems of the world. Estados Unidos: Oxford University Press.

Harvard

Oxfor University Press, . (1991). National health systems of the world. Estados Unidos: Oxford University Press.

MLA

Oxfor University Press, . National health systems of the world. Estados Unidos: Oxford University Press. 1991.