Have Dean Koontz and Bernhard Schlink both written at least one novel?
Bernhard Schlink Bernhard Schlink (born 6 July 1944 in Bielefeld) is a German lawyer and writer. His novel "The Reader", first published in 1995, became an international bestseller.
Katherine Kurtz Katherine Irene Kurtz is an American fantasy writer, known for her sixteen historical fantasy novels in the "Deryni" series. She also wrote several occult alternate history novels in her "Templar" series, and urban fantasy novels in her "Adept" series.