From Mr. DiPrima's 1988 obituary (linked above):
Mr. DiPrima was the first to sell pizza - then called 'tomato pie' - in the resort, his wife said. He started transporting the pizza from the bakery in nearby Lawrence to Salisbury Beach in 1940, then sold it for 15 cents a slice... She and her husband made everything from scratch - the sausages, the pizza dough and sauces, the meat pies and meatballs - and bought only fresh produce for the sauces, menu items and garnishes.
'We were a team, inseparable. We even cooked together at home,' his wife said.