Table: stem_cell_bill
Columns: congress
short_title
bill_number_s
date_introduced
sponsor_s
of_cosponsors

Question: Who was the sponsor for the bill introduced February 28, 2005 with cosponsors less than 200?
SQL: SELECT "sponsor_s" FROM stem_cell_bill WHERE "of_cosponsors" < 200 AND "date_introduced" = 'february 28, 2005'