Bohemian families

My ancestors arrived in the USA from Bohemia and settled in Iowa. At this time I am researching Martin Novy (Novey, Novee). The census records have his name spelled several ways. I am also interested in the Kupa, Krotz, and Spevacek families.
I wish for any information aboutt these families before theyentered the USA.
Thank you,
Viola Hochstettler