APA
Kregel J. A., . (1976). Theory of capital. London: Macmillan.
Chicago
Kregel J A, . 1976. Theory of capital. London: Macmillan.
Harvard
Kregel J. A., . (1976). Theory of capital. London: Macmillan.
MLA
Kregel J A, . Theory of capital. London: Macmillan. 1976.