Keene, C. (1930). Nancy Drew Mystery Stories: The Hidden Staircase No. 2. Grosset & Dunlap.
Chicago-čujuhus (17. p.)Keene, Carolyn. Nancy Drew Mystery Stories: The Hidden Staircase No. 2. New York: Grosset & Dunlap, 1930.
MLA-čujuhus (9. p.)Keene, Carolyn. Nancy Drew Mystery Stories: The Hidden Staircase No. 2. Grosset & Dunlap, 1930.
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