Murphy, G., & Dale, L. A. (1961). Challenge of psychical research: A primer of parapsychology. Harpers.
Lua i Stíl Chicago (17ú heag.)Murphy, Gardner, agus Laura A. Dale. Challenge of Psychical Research: A Primer of Parapsychology. New York: Harpers, 1961.
Lua MLA (8ú heag.)Murphy, Gardner, agus Laura A. Dale. Challenge of Psychical Research: A Primer of Parapsychology. Harpers, 1961.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.