You can find books on sustainable transportation by doing a subject search in DELCAT, the University of Delaware Libraries' catalog. The Library of Congress Subject Headings, used in DELCAT, has subject keywords that enable you to identify books, journal articles, and gov docs on your topic. Video tutorial on using DELCAT.
DELCAT Search Example:
1) Wearable technology (UD Library materials only)
Search syntax => Subject contains the exact phrase Wearable Technology
2) "Smart Helmets" (UD and non-UD chapters, books and e-books)