زراعة
Unersity of Pretoria, New Zealand
University of Notre Dame
M.I.T. Theses and E-Theses Online
Harvard University - Hollis Catalog
Dissertations & Theses (ETD)
NCSU NC State Theses and Dissertations
the Pennsylvania State University's electronic Theses and Dissertations Archives
Uppsala Universitiet
University of Florida George A. Smathers Libraries
UF theses and dissertations