1. 2070 ATC (Advanced Transportation Controllers) Equipment Parts and Accessories.
http://esbd.cpa.state.tx.us/bid_show.cfm?bidid=139594
. Accessed 31 May 2017
2. Search Federal, State, and Local Government Contracts, Government Bids, and RFPs.
https://www.bidcontract.com/government-contracts-bids/search-government-Bids-Contracts.aspx?s=2070&t=FE&is=0
. Accessed 31 May 2017
3. The Traffic Signal Museum: Eagle Signal Model EF-15 Traffic Controller (2015).
http://www.trafficsignalmuseum.com/pages/ef15.html
4. 1103 v03 - NTCIP Transportation Management Protocols (TMP) v03 (2017).
https://www.ntcip.org/library/standards/default.asp?documents=yes&qreport=no&standard=1103%20v03
5. AASHTO: American association of state highway and transportation officials.
https://www.transportation.org/