1.
- Publishers' international directory with ISBN index. 2, U. S. A. - Zimbabwe / edit. Helmut Opitz, Karl Heinz Strasser. - 15th ed. - München : Saur, 1988 - s. 5, 907-1770(Handbook of international documentation and information; vol. 7) ISBN 3-598-20537-6 [1, currently available 1]
- Chapters, articles