1. American Foundation for the Blind,
http://www.afb.org/section.aspx?SectionID=40&TopicID=168&DocumentID=907
2. Taipei e-bus System,
http://www.e-bus.taipei.gov.tw/new/english/en_index_6_1.aspx
3. Department of Statistics, Ministry of the Interior, Taiwan,
http://statis.moi.gov.tw/micst/stmain.jsp?sys=100
4. Ezaki, N., Bulacu, M., Schomaker, L.: Text detection from natural scene images towards a system for visually impaired persons. In: Proceeding of ICPR 2004, Tampa, FL, vol. 2, pp. 683–686 (2004)
5. Lecture Notes in Computer Science;C.-M. Tsai,2013