APA (7th ed.) Citation

Williams, S. Free as in Freedom: Richard Stallman's Crusade for Free Software.

Chicago Style (17th ed.) Citation

Williams, Sam. Free as in Freedom: Richard Stallman's Crusade for Free Software.

MLA (9th ed.) Citation

Williams, Sam. Free as in Freedom: Richard Stallman's Crusade for Free Software.

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