AS 60: In most VSMs, special thermal devices or heat exchanger pipes are installed to maintain the permafrost in a stable condition around the supports., 1976-03, PCA0002-1a-33, Folder: PCA0002-1a. Alyeska Pipeline Service Company : Trans-Alaska Pipeline Construction Collection, 1976-1977, PCA 2. Alaska State Library - Historical Collections Finding Aids. https://alaska.libraryhost.com/repositories/2/archival_objects/17309 Accessed February 22, 2025.