On the St. Louis CIN web site, you may find electronic versions of:
1947 Comprehensive Plan for the City of St. Louis History of the Physical Growth of the City of St. Louis History of St. Louis Neighborhoods series, by Norbury Wayman Harland Bartholomew: His Contributions to American Urban Planning, by Eldridge Lovelace
On the Library of Congress web site you may find in electronic form: Pictorial St. Louis, the great metropolis of the Mississippi valley; a topographical survey drawn in perspective A.D. 1875, by Camille N. Dry; designed & edited by Rich. J. Compton.
Other books about St. Louis may be found at the St. Louis Public Library, and a variety of other research institutions.