Answered By: Bette Rathe
Last Updated: Dec 05, 2016     Views: 139

This depends on the style you are using:

  • Chicago and MLA say add 's as in: Mills becomes Mills's
  • APA says add 's to singular names ending in s, except if the name ends in an unpronounced s and then use only an apostrophe: Descartes becomes Descartes'