My great great grandmother was Johanna Portelli, Schmidt, Peitl. She immigrated to America in approximately 1870-1875. She came with her husband, Johann Peitl, and children Anna and John Peitl, and Frank and Mary Schmidt. I have been unable to find their names on any passenger lists. The family came from the Zwittau area of Bohemia, Austria. Any ideas about how to find immigration information?