If you have already found relevant materials, the citations - or bibliographic records - in those sources are a great way to expand your bibliography. You will find that journal titles are often abbreviated in citations. Here is a website that can help you determine the full title: Abbreviations of Names of Serials (from the Caltech Library System.)

The primary source for citation searching in City and Regional Planning is ISI's Social Sciences Citation Index Expanded. You can search for articles themselves, citations of an article, or citations of a specific author. The number of times a given article has been cited frequently indicates how influential it has been. The articles that cite the original article could also be useful sources.