by University of Colorado (Boulder campus)

1906

by University of Illinois (Urbana-Champaign campus). Bureau of Educational Research

1927

by University of Colorado

1908

by University of Colorado

1911

by Cornell University. Agricultural Experiment Station

1897

by Cornell University. Agricultural Experiment Station

1897

by Cornell University. Libraries

1891

by University of Tennessee, Knoxville. Agricultural Experiment Station

1899

by Syracuse University

1924

by University of Manitoba

1926

by University of Illinois at Urbana-Champaign. Agricultural Experiment Station

1912

by University of Cambridge

1906