International ISBN Agency. (1990). Publishers' international ISBN directory: Publisher's international directory with ISBN index and the 11th edition of the international ISBN publishers' directory (17th ed.). Munchen ; , Berlin ; , New York.
Παραπομπή σε μορφή Chicago (17η εκδ.)International ISBN Agency. Publishers' International ISBN Directory: Publisher's International Directory with ISBN Index and the 11th Edition of the International ISBN Publishers' Directory. 17th ed. K.G. Saur : International ISBN agency : R R Bowker: Munchen ; , Berlin ; , New York, 1990.
Παραπομπή σε μορφή MLA (9th εκδ.)International ISBN Agency. Publishers' International ISBN Directory: Publisher's International Directory with ISBN Index and the 11th Edition of the International ISBN Publishers' Directory. 17th ed. Munchen ; , Berlin ; , New York, 1990.