Books for Elementary Children:

En Todas Partes & En Cualquier Lugar by Pimm van Hest & Sassafras De Bruyn (Spanish language) 
A little girl processes the loss of her mother with the help of those around her and finds her mother’s presence in memories comforting.

The Heart and the Bottle by Oliver Jeffers
After the loss of a father/grandfather (book isn’t specific), a young girl bottles up her heart/hurt to protect herself. Later, someone else comes along to spur her wonder/curiosity of life and helps her take her heart out of the bottle and process her loss.

Maybe Tomorrow? by Charlotte Agell
Two animals create a friendship that helps the hurt/loss that one animal carries to grow lighter. 

The Three Lucys by Hayan Charara
Story of a little boy in Lebannon who loses one of this three cats due to evacuation from bombings. When he returns home he only finds two of the three cats survived… and works to process the losses.

Books for Older Elementary/Middle School

My Father’s Words by Patricia MacLachlan
A pair of siblings process the loss of their father with the help of their mom, neighbor friend, and finding ways to help others.

Books for Adults to Help Children Process Grief

The Grief Tower by Lauren Wells
This book provides a framework for helping kids and parents unpack losses, fears, crises, significant events, and periods of anxiety/depression. 

When Children Grieve: For Adults to Help Children Deal with Death, Divorce, Pet Loss, Moving, and Other Losses by J. W. James & R. Friedman
There are guidelines for helping children develop a lifelong, healthy response to loss.The authors wrote this book to free children from the false idea of “not feeling bad” and to empower them with positive, effective methods of dealing with loss.