The Minneapolis Star Tribune said Hassler, the author of more than 15 novels for adults and young adults, died Thursday morning.

Among his works are "Staggerford," "Grand Opening" and "The Love Hunter."

"Staggerford" was named Novel of the Year in 1978 by the Friends of American Writers. "Grand Opening" was chosen Best Fiction of 1987 by the Society of Midland Authors. His novel, "A Green Journey," was adapted for TV as "The Love She Sought," starring Angela Lansbury.

Hassler, a former high school English teacher, also held the positions of Regents Professor Emeritus and Writer-in-Residence at St. John's University in Collegeville, Minn.

He received fellowships from the John Simon Guggenheim Foundation and the Minnesota State Arts Board. Hassler received honorary doctorate degrees from Assumption College, the University of North Dakota and the University of Notre Dame.

Hassler was born in Minneapolis in 1933.