Preservation Brief 30, by Anne E. Grimmer and Paul K. Williams
Online Version:
https://www.nps.gov/tps/how-to-preserve/briefs/30-clay-tile-roofs.htm
PDF Version:
https://www.nps.gov/tps/how-to-preserve/preservedocs/preservation-briefs/30Preserve-Brief-ClayRoofs.pdf