Lars has a book.
Fritz has a house.
How do I show possession using the genitive ending "s" for a proper noun that ends in an "s" or "z"?
Das ist Lars(?) Buch.
Das ist Fritz(?) Haus.
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Sign up to join this communityLars has a book.
Fritz has a house.
How do I show possession using the genitive ending "s" for a proper noun that ends in an "s" or "z"?
Das ist Lars(?) Buch.
Das ist Fritz(?) Haus.
As presumed in the question the "normal" genitive-"s" would look strange (Larss Buch, Fritzs Haus). So the official rules (§ 96.1) and also rule 16 at Duden Sprachwissen say, that the genitive-"s" is omitted and an apostroph is used to show the omission:
Das ist Lars' Buch.
Das ist Fritz' Haus.
In northern Germany, there is/was the ending "-ens" used in colloquial speech for masculine names, so it would read:
Das ist Larsens Buch.
Das ist Fritzens Haus.
But this ending is very old-fashioned.
Note that the apostrophe has no correlation with the genitive-"'s" used in English. As mentioned it only denotes the omission of letters.