Surname LUKAC^ and GAZDIK show up in Slovak Republic's phone book. www.zoznamst.sk
Have you located a place of birth for either of them?
The 1930 US census would say if they were naturalized citizen or alien. If not naturalized but lived pass 1940 then there is an Alien Registration Form which would have a place of birth. www.surnamenavigator.orgwww.iabsi.com/gen/public