Start with high-confidence death & dying for teens books, then narrow by subgenre or adjacent topics.
Dying
Pat McNees
Grieving With Hope
Samuel J.I.V. Hodges, Kathy Leonard
Grieving a Suicide
Albert Y. Hsu
Good Grief
Granger E. Westberg
The Other Side of Sadness
George A. Bonanno
Grief Day by Day
Jan Warner, Amanda Bearse