Who were the Ivy League champions of football 1930s?

1931-Cornell (3-1)
1932-Army (3-0); Brown (3-0)
1933-Princeton (5-0)

1934-Navy (3-0)
1935-Princeton (6-0)

1936-Dartmouth (5-0-1)
1937-Dartmouth (4-0-2)
1938-Cornell (3-0-1)
1939-Cornell (4-0)