Não informado. (1968). Educational Studies in Mathematics. D. Reidel Publishing.
Lua i Stíl Chicago (17ú heag.)Não informado. Educational Studies in Mathematics. Dordrecht, Holanda: D. Reidel Publishing, 1968.
Lua MLA (8ú heag.)Não informado. Educational Studies in Mathematics. D. Reidel Publishing, 1968.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.