by Purdue University. Dept. of Engineering Extension

1930

by Purdue University. Dept. of Engineering Extension

1924

by Purdue University. Department of Engineering Extension

1925

by Purdue University, Lafayette, Ind. Engineering Extension Department

1930

by Purdue University. Department of Engineering Extension

1929

by Purdue University. Engineering Extension Service

1922

by Purdue University

1923

by Purdue Univesity. Dept. of Engineering Extension

1927

by Purdue University. Department of Engineering Extension

1923

by Purdue University. Department of Agricultural Extension

1922

by Purdue University. Engineering Extension Service

1924

by Purdue University. Department of Agricultural Extension

1923