linsel, h., & sack, k. (1965). theoretical problems of investment planning. National Planning Institute.
Chicago (17e ed.) Bronvermeldinglinsel, hermann, en kurt sack. Theoretical Problems of Investment Planning. cairo: National Planning Institute, 1965.
MLA (9e ed.) Bronvermeldinglinsel, hermann, en kurt sack. Theoretical Problems of Investment Planning. National Planning Institute, 1965.