United Nations. Department of Technical Cooperation for Development. (1991). Ground water in western and central Europe. United Nations.
Παραπομπή σε μορφή Chicago (17η εκδ.)United Nations. Department of Technical Cooperation for Development. Ground Water in Western and Central Europe. New York: United Nations, 1991.
Παραπομπή σε μορφή MLA (9th εκδ.)United Nations. Department of Technical Cooperation for Development. Ground Water in Western and Central Europe. United Nations, 1991.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.