Ryan, W. J. L. (1958). Price theory. Macmillan; St. Martin's Press.
Lua i Stíl Chicago (17ú heag.)Ryan, William James Louden. Price Theory. London, New York: Macmillan; St. Martin's Press, 1958.
Lua MLA (9ú heag.)Ryan, William James Louden. Price Theory. Macmillan; St. Martin's Press, 1958.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.