"FHU Reference No. 03-217.", "May 2004.", Description based on online resource; title from PDF title page; (viewed September 2012), Mode of access: World Wide Web.
jointly prepared by Felsburg Holt & Ullevig [and] Colorado Department of Transportation Region 5 Traffic Section., "May 2009."--Title page., "Year 2008."--Cover., Online resource; title from PDF title page; (viewed June 2016), FHU Reference No. 08-137.
jointly prepared by Felsburg Holt & Ullevig [and] Colorado Department of Transportation Region 4 Traffic Section., "June 2013.", FHU Reference No. 11-111-13, Online resource; title from PDF title page; (viewed June 2016)
jointly prepared by Felsburg Holt & Ullevig [and] Colorado Department of Transportation Region 3 Traffic Section., "June 2011"--Title page, "Year 2010"--Cover., FHU Reference No. 10-010-16, Online resource; title from PDF title page; (viewed June 2016)
"FHU Reference No. 07-320-01, 08-232-02, 08-232-06.", "August 2009.", Description based on online resource; title from PDF title page; (viewed September 2012), "Year 2008."--Cover., Mode of access: World Wide Web.
"FHU Reference No. 08-232-01.", "January 2009.", Description based on online resource; title from PDF title page; (viewed September 2012), Cover carries date of 2008., Mode of access: World Wide Web.
"FHU Reference No. 07-268", "May 2008.", Description based on online resource; title from PDF title page; (viewed September 2012), Mode of access: World Wide Web.
jointly prepared by Felsburg Holt & Ullevig [and] Colorado Department of Transportation Region 2 Traffic Section., "June 2013.", FHU Reference No. 112266-07, Online resource; title from PDF title page; (viewed June 2016).
jointly prepared by Felsburg Holt & Ullevig [and] CDOT Region 6 Traffic and Safety Section., "November 2010.", Online resource; title from PDF title page (viewed June 2016), FHU Reference No. 08-133-07