Several sources state that the tenor Juan Spiwak (also Spivak and Spiwack) was Slovenian. This seems to be false, very likely he was born in Philadelphia (USA) to Russian parents of Jewish descent and spent his childhood in Odessa with his grandparents. He first performed in Vienna and later all over Germany. Due to the political situation there, he immigrated to America, where he re-applied for American citizenship. More information at historicaltenors.net.
His recordings are excellent - here an aria from Lohengrin.