linsel, h., & sack, k. (1965). theoretical problems of investment planning. National Planning Institute.
Lua i Stíl Chicago (17ú heag.)linsel, hermann, agus kurt sack. Theoretical Problems of Investment Planning. cairo: National Planning Institute, 1965.
Lua MLA (9ú heag.)linsel, hermann, agus kurt sack. Theoretical Problems of Investment Planning. National Planning Institute, 1965.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.