Sedevacantism is the extreme "radtrad" belief that there is no legitimate pope. It means literally in Latin, "the seat is vacant." Perhaps the most famous current exponent is Gerry Matatics.
* * *
"HABEMUS PAPAM"? by Karl Keating (This Rock, July/August 1995)
White Smoke, Valid Pope, by Rev. Brian Harrison, O.S. (This Rock, March 2001)
Do-It-Yourself Popes: The Wacky World of Sedevacantists, by Michael Petek (This Rock, March 2000)
Mr. X, by Karl Keating (This Rock, June 1995)
The Errors of Sedevacantism and Ecclesiastical Law, by John Salza
A Heretical Pope? (Michael Davies)
A Refutation of the Heresy of Sedevacantism (Shawn McElhinney)
***