Geraldine:

Have you tried the Library of Congress (DC -- I had good luck finding early
20th century periodicals put out by the building trades) or Avery Library
at Columbia University (New York)?  You also might try the University of
Pennsylvania (Philadelphia) or other schools with grad programs in historic
preservation or architectural history (Univ. of Virginia or Cornell in
Ithaca, NY).  You also might contact the National Building Museum or the
National Trust for Historic Preservation, both in Washington, DC.

Good Luck!