Delfgaauw, B. (1969). Twentieth-century philosophy. Magi Books.
Lua i Stíl Chicago (17ú heag.)Delfgaauw, Bernard. Twentieth-century Philosophy. Albany, N.Y.: Magi Books, 1969.
Lua MLA (8ú heag.)Delfgaauw, Bernard. Twentieth-century Philosophy. Magi Books, 1969.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.