Mark, J., Spellman, F., & Peale, N. V. (1954). Understanding. K. H. Volk.
Lua i Stíl Chicago (17ú heag.)Mark, Julius, Francis Spellman, agus Norman Vincent Peale. Understanding. New York: K. H. Volk, 1954.
Lua MLA (8ú heag.)Mark, Julius, et al. Understanding. K. H. Volk, 1954.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.