apostrophe possessive
The mark that shows ownership.
Add ’s to a singular noun, even one that already ends in s: the boss’s desk, James’s book, Jesus’s name, Socrates’s trial. Add only an apostrophe to a regular plural that already ends in s: the bosses’ desks, the Joneses’ house. Joint ownership takes one mark on the last name: Maria and Tom’s apartment. Separate ownership takes a mark on each: Maria’s and Tom’s apartments.
Examples
Use James’s report is late.
Use Jesus’s parables
Use the teachers’ lounge
Avoid the teacher’s lounge (If more than one teacher shares it.)
Use Luis and Ana’s lease
News and magazines often drop the second s after any singular name that already ends in s: James’, Socrates’, the boss’ desk. Older print does the same.