APA (7th ed.) Citation

Hardy, C. (2009). The Aural System Being the Most Direct, the Straight-Line Method for the Simultaneous Fourfold Mastery of a Foreign Language. Project Gutenberg.

Chicago Style (17th ed.) Citation

Hardy, Charles. The Aural System Being the Most Direct, the Straight-Line Method for the Simultaneous Fourfold Mastery of a Foreign Language. Project Gutenberg, 2009.

MLA (9th ed.) Citation

Hardy, Charles. The Aural System Being the Most Direct, the Straight-Line Method for the Simultaneous Fourfold Mastery of a Foreign Language. Project Gutenberg, 2009.

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