APA (7th ed.) Citation

Mark Twain. (2010). A double barrelled detective story. Project Gutenberg.

Chicago Style (17th ed.) Citation

Mark Twain. A Double Barrelled Detective Story. To be supplied: Project Gutenberg, 2010.

MLA (8th ed.) Citation

Mark Twain. A Double Barrelled Detective Story. Project Gutenberg, 2010.

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