APA (7th ed.) Citation

Ambler, E. (1987). The dark frontier (Collins English Library level 6). William Collins Sons.

Chicago Style (17th ed.) Citation

Ambler, Eric. The Dark Frontier (Collins English Library Level 6). William Collins Sons, 1987.

MLA (8th ed.) Citation

Ambler, Eric. The Dark Frontier (Collins English Library Level 6). William Collins Sons, 1987.

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