You would probably have to write the Nassau Co. Health Dept., they'd be the ones who would issue permits for restaurants. You could trying phoning first, but doubtful they'd of gone back and added 1940 era records to their computer system. That also makes it doubtful the records would be online. But at least a phone call would tell you if the records are onsite or transferred to their County Hall of Records. Then you'd know where to address your queury.