Slotboom, Erik. "Notes and Index"(PDF). Houston Freeways. Self-published. Archived from the original(PDF) on September 7, 2006. Retrieved September 7, 2006.
Slotboom, Erik. "The Loop, Interstate 610"(PDF). Houston Freeways. Self-published. Archived from the original(PDF) on December 9, 2006. Retrieved December 15, 2006.
Transportation Planning and Programming Division (n.d.). "Highway Designations Glossary". Texas Department of Transportation. Archived from the original on July 10, 2022. Retrieved May 20, 2020.
"100 Congested Roadways". Texas Department of Transportation. Archived from the original on December 10, 2014. Retrieved December 8, 2014.
Transportation Planning and Programming Division (n.d.). "Highway Designations Glossary". Texas Department of Transportation. Archived from the original on July 10, 2022. Retrieved May 20, 2020.
Slotboom, Erik. "Notes and Index"(PDF). Houston Freeways. Self-published. Archived from the original(PDF) on September 7, 2006. Retrieved September 7, 2006.
Slotboom, Erik. "The Loop, Interstate 610"(PDF). Houston Freeways. Self-published. Archived from the original(PDF) on December 9, 2006. Retrieved December 15, 2006.