Grief (novel)
During the course of the novel, the ideas of the stages of grief are introduced. The stages are denial, anger, depression, and acceptance. The narrator, as well as other characters in the story, slowly passes through these stages in trying to deal with death.
Kübler-Ross model
George Bonanno, Professor of Clinical Psychology at Columbia University, in his book "The Other Side of Sadness: What the New Science of Bereavement Tells Us About Life After a Loss", summarizes peer-reviewed research based on thousands of subjects over two decades and concludes that a natural psychological resilience is a principal component of grief and that there are no stages of grief to pass. Bonanno's work has also demonstrated that absence of grief or trauma symptoms is a healthy outcome.