Keene, C. (1930). Nancy Drew Mystery Stories: The Hidden Staircase No. 2. Grosset & Dunlap.
Lua i Stíl Chicago (17ú heag.)Keene, Carolyn. Nancy Drew Mystery Stories: The Hidden Staircase No. 2. New York: Grosset & Dunlap, 1930.
Lua MLA (9ú heag.)Keene, Carolyn. Nancy Drew Mystery Stories: The Hidden Staircase No. 2. Grosset & Dunlap, 1930.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.