Provide at least 2 references that have helped you to think through this topic and its significant geographic/spatial questions. For each reference briefly explain how it has helped you think about the topic (do not simply copy the abstract). At this point these references do not have to be from peer-reviewed journals, but it will be very helpful for you to review the peer-reviewed literature now or in the near future. Peer reviewed articles will often go into more detail regarding theoretical models, data sources, methods of analysis, results, and limitations than non-peer reviewed articles. Please put your citations in ASCE format.