Europa Publications & Europa Publications. (1971). The world of learning 1970-71 (21. ed.). Staples Printers Rochester.
Chicago Style (17th ed.) CitationEuropa Publications and Europa Publications. The World of Learning 1970-71. 21. ed. Rochester: Staples Printers Rochester, 1971.
MLA (9th ed.) CitationEuropa Publications and Europa Publications. The World of Learning 1970-71. 21. ed. Staples Printers Rochester, 1971.