Hirschfeld, G., & Boulding, K. E. The people: Growth and survival : first cycle. Aldine Pub. Co. c1973.
Cita Chicago (17th ed.)Hirschfeld, Gerhard, i Kenneth E. Boulding. The People: Growth and Survival : First Cycle. Chicago: Aldine Pub. Co. c1973.
Cita MLA (9th ed.)Hirschfeld, Gerhard, i Kenneth E. Boulding. The People: Growth and Survival : First Cycle. Aldine Pub. Co. c1973.
Atenció: Aquestes cites poden no estar 100% correctes.