by University of Iowa. Child Welfare Research Station, University of Iowa

1924

by Pennsylvania State University. Agricultural Extension Service

1924

by State University of Iowa

1925

by Yale University

1920

by University of North Carolina (1793-1962). University Extension Division

1927

by University of North Carolina (1793-1962). University Extension Division

1926

by Columbia University. Teachers College

1925

by Columbia University. Teachers College

1927

by University of Iowa

1927

by University of North Carolina (1793-1962)

1926

by Iowa State University. Cooperative Extension Service

1928

by Columbia University. Teachers College

1930