[Grammar] possessive with singular nouns ending with 's'

[marker]

I was taught that singular nouns take 's in the possessive case even when they end with 's' eg.

Charles's book

Is this rule outdated? Now in grammar books it's stated that we can't say eg. Socrates's garden but Socrates' garden.

Thank you for replies

 

[Grumpy]

It all depends on how the spoken version sounds. Thus, "Charles's book" rolls smoothly off the tongue, whereas "Socrates's" sounds as though there are far too many "S's" present.

 

[MikeNewYork]

I was taught that singular nouns take 's in the possessive case even when they end with 's' eg.

Charles's book

Is this rule outdated? Now in grammar books it's stated that we can't say eg. Socrates's garden but Socrates' garden.

Thank you for replies

There isn't general agreement on this issue. Grammar books and style guides often use different approaches. See the comments on this site: Possessive Forms