APA (7th ed.) Citation

Clarke, I. C. (1913). The secret citadel / by I.C. Clarke. Hutchinson.

Chicago Style (17th ed.) Citation

Clarke, I. C. The Secret Citadel / by I.C. Clarke. Hutchinson, 1913.

MLA (9th ed.) Citation

Clarke, I. C. The Secret Citadel / by I.C. Clarke. Hutchinson, 1913.

Warning: These citations may not always be 100% accurate.