Genitive of Sunrise: Sunrise' or Sunrise's [duplicate]
What is the possessive of a noun ending in ‑s? Are these both right, or is the second one wrong?
the boys' books
the boss' car
Solution 1:
Your example sentences confuse two different problems.
For nouns that are plural (such as "boys"), the possessive is formed in writing by adding an apostrophe after the plural -s. This is pronounced the same as the plural and the singular possessive:
The boys' books [boys' sounds like boys]
For singular nouns that end in -s, the possessive is formed by adding -'s, just as with other nouns. This is pronounced as if the spelling were es:
The boss's car [boss's sounds like bosses]
There is a partial exception for proper names that end in s. These names sometimes form their possessive by simply adding an apostrophe, and without changing their pronunciation:
Confucius' sayings
Jesus' teachings
However, this doesn't apply if the name ends with a letter other than s, even if it's pronounced with an s. These names form their possessive as normal:
Marx's theories
In the opposite case of a name which ends in a silent s, the possessive is usually formed by adding an apostrophe in writing, but the apostrophe causes the silent s to be pronounced:
Camus' novels [the final -s in Camus is not silent here]
Solution 2:
On singular nouns that end with an "s" or "z" sound, Wikipedia has a say. According to the article, there is no hard and fast rule on this one and different "authorities" prefer different styles.
See also St. James's park and St. James' park.