Dr. Boris Theodore SOKOLOFF came US abt 1928, as a professor; his residence was Nice, France. He petitioned for naturalized 1929.. SS has a different b/date, so hopefully he is same person who d Lakeland FL. He had at least 2 wives.
Do you have reason to believe his parents and siblings came to US?
You might check with the Lakeland Public Library for obit...it may mention siblings.