By Salinas Cantú, Hernán.
México : McGraw-Hill. Interamericana .
141 p. 970-10-2041-3

By Escardó, Florencio.
Buenos Aires : A Peña Lillo .
110 p. 84-8203-001-9

By Coe, Rodney M.
Madrid : Alianza Editorial .
439 p. 84-206-2055-6

By Charles Dunlop, Clarense Eduardo.
Santo Domingo : Corripio .
361p.

By Sánchez González, Miguel Ángel.
Masson .
xxiii, 592 p. 84-458-0733-1

OMS .
24 p.