Liefeld, Elsa Thusnelda2017-04-202017-04-2019411941b14738132(OCoLC)07877710(OCoLC)ocm07877710https://hdl.handle.net/2144/21351Thesis (Ph.D.)--Boston University, 1941. This item was digitized by the Internet Archive.en-USBased on investigation of the BU Libraries' staff, this work is free of known copyright restrictionsThesis/Dissertation