Παραπομπή APA

Sapsford,David, & Ladd,James. (1978). Essential economics. Hart-Davis Educational.

Παραπομπή Chicago Style

Sapsford,David, και Ladd,James. Essential Economics. Great Britain: Hart-Davis Educational, 1978.

Παραπομπή MLA

Sapsford,David, και Ladd,James. Essential Economics. Hart-Davis Educational, 1978.