SpringerLink (Online service), Langmann, H., Schleicher, D., & Gronau, H. (2011). 50th IMO - 50 years of international mathematical olympiads. Springer-Verlag Berlin.
Chicago Style (17th ed.) CitationSpringerLink (Online service), Hanns-Heinrich Langmann, Dierk Schleicher, and Hans-Dietrich Gronau. 50th IMO - 50 Years of International Mathematical Olympiads. Berlin, Heidelberg: Springer-Verlag Berlin, 2011.
MLA (8th ed.) CitationSpringerLink (Online service), et al. 50th IMO - 50 Years of International Mathematical Olympiads. Springer-Verlag Berlin, 2011.
Warning: These citations may not always be 100% accurate.