* Pollard, Jeanne. Building Toothpick Bridges. Palo Alto, CA: Dale Seymour Publications, 1988. Ages 9-12.

* Gralla, Preston, Dave Feasey and Mina Reimer. How Cities Work: Open Your Eyes to the Wonders of the Urban Environment. Emeryville, CA: Ziff-Davis Press, 1995. Ages 12-18.

* Parker, Philip. Global Cities: Investigating the Ecology of Out Towns and Cities. New York Thomson Learning, 1995. Ages 12-16.