[Sid Rich]

Change "Larry Parks' day" to "Larry Parks's day".

The first rule in Strunk & White's "Elements of Style" is "Form the possessive singular of nouns by adding 's."

[Sid Rich]

Several Strunk fans struck at once.

[Gumlegs]

You're right. I think there's (a contraction, not a possessive), more on the subject in Fowler.

[MoralSense]

Yep, that's what Strunk says all right, and I do it, but editors almost invariably change it in the case of last names that end in "s." This dates from -- believe it or not -- a Time magazine style decision in the 1950s, which also eliminated the comma before "and" in a series. Reason? It saved printer's ink. Hundreds of thousands of dollars's worth per year.