Hi. One thing I have always struggled with is the correct grammar and punctuation when using the possessive form of a proper name in that ends in the letter 's', such as Jones. The example is, "I walked over to Sarah Jones's house on Saturday."

I think the correct spelling is "Jones's", but I have seen it spelled many times without the final s, and in fact, I have even seen it spelled without the apostrophe and final s, which I am sure is not correct.

Please let me know the rule.