APA Style

ELTON, E, J., GRUBER, M, J. (1991). Modern Portfolio Theory and Investment Analysis; Fourth Edition (4). New York: John Wiley & Sons.

MLA Style

ELTON, EDWIN, J.., GRUBER, MARTIN, J.. "Modern Portfolio Theory and Investment Analysis; Fourth Edition". 4 New York: John Wiley & Sons, 1991. Text.