Harvard University Biographical Files (Find It @ Archives). See files for Henry Hobson Richardson and James Warren Sever.
Harvard University Property Information Resource Center (PIRC) website
H.H. Richardson and His Office: A Centennial of his move to Boston: Selected Drawings (Find It @ Harvard) by James F. O'Gorman. Cambridge: Department of Printing and Graphic Arts, Harvard College Library, 1974.
H.H. Richardson, Complete Architectural Works by Jeffrey Karl Oschner. Cambridge: M.I.T. Press, 1982.
"Henry Hobson Richardson" by Phillips Brooks. Harvard Monthly Volume 3 (October 1886): 1-7
Henry Hobson Richardson drawings (Find It @ Harvard). Houghton Library. MS Typ 1096.