Use a database or print index to retrieve citations to journal articles. Then use Journal Finder to determine whether articles are available in print or online in a fulltext database. Use Interlibrary Loan to obtain copies of articles from other libraries.
Primary Databases for Geography
If you have never used the Digital Sanborn Maps Online database, I recommend you begin by reading through the guide created by Dr. Ralph Taylor from Criminal Justice. If you need a Pennsylvania Sanborn map, you can easily download one for free from the Penn State website.