Articles
1. https://www.aarp.org/content/dam/aarp/livable-communities/learn/transportation/meeting-transportation-needs-in-an-aging-friendly-community-aarp.pdf
2. http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=1520&context=jpt
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5656732/
4. http://www.nctadrc.org/documents/ATW_Transportation.pdf