APA (7th ed.) Citation

(1690). An answer to a paper, entituled, A letter to a friend.

Chicago Style (17th ed.) Citation

An Answer to a Paper, Entituled, A Letter to a Friend. [London?], 1690.

MLA (9th ed.) Citation

An Answer to a Paper, Entituled, A Letter to a Friend. 1690.

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