Del Rey published The White Dragon by Anne McCaffrey in 1978, the third book in the original Dragonriders of Pern trilogy, along with new editions of the first two books.
As for the third, Luserke's attempt to stir Anne McCaffrey's (Dragonriders of Pern series) interest in his project was a failure, so he tried Julian May (Saga of Pliocene Exile).
Dragonsblood, a 2005 science fiction novel by Todd McCaffrey in the "Dragonriders of Pern" series