On Ancestry site:
1930 Census shows
Newark, Ward Ninth, Block 971, April 5th, 1930
Address 58 Huntington Terrace
William Petrin, age 53, age at marriage 27, born in Switzerland, native language French, arrived in 1900, alien status, (Naturalized was written and then crossed out) employed as a waiter in a restaurant.
Louise Petrin, age 42, age at marriage 19, born in Northern Ireland, arrived in 1905, alien status.
Walter Petrin, age 19, Single, attended school 1929-Yes, born in New Jersey, emloyed none
Hope these are your people and this helps
Monica