Kinderen, Dirk (18 May 2022). "Interpretation Letter Ref No. 22-0019"(PDF). phmsa.dot.gov. Pipeline and Hazardous Materials Safety Administration. Archived from the original(PDF) on 19 August 2022. Retrieved 24 January 2023.
Kinderen, Dirk (18 May 2022). "Interpretation Letter Ref No. 22-0019"(PDF). phmsa.dot.gov. Pipeline and Hazardous Materials Safety Administration. Archived from the original(PDF) on 19 August 2022. Retrieved 24 January 2023.