1. World Motor Vehicle Statistics: Japan Automobile Manufacturers Association (JAMA),2013
2. PTW Safety: IMMA's Contribution to the Decade of Action for Road Safety 2011–20, International PTW Manufacturers Association (IMMA),2010
3. Research regarding the roles and limitations of motorbikes as urban transportation means in developing nations; research investigation project report (Japanese text only), IATSS;Fukuda,2003
4. Research regarding the roles and limitations of motorbikes as urban transportation means in developing nations (II); research investigation project report;Fukuda,2004
5. Motor Vehicle Statistics of Japan 2013: JAMA,2013