Postal, Telegraph and Telephone International. (1961). PTTI study trip in West and Central Africa: 26 December 1960 - 11 February 1961.
Chicago-Zitierstil (17. Ausg.)Postal, Telegraph and Telephone International. PTTI Study Trip in West and Central Africa: 26 December 1960 - 11 February 1961. Berne, 1961.
MLA-Zitierstil (9. Ausg.)Postal, Telegraph and Telephone International. PTTI Study Trip in West and Central Africa: 26 December 1960 - 11 February 1961. 1961.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.