Thierry Bokanowski & Leticia Glocer Fiorini 
On Freud’s ‘Mourning and Melancholia’ [PDF ebook] 

Both melancholia and mourning are triggered by the same thing, that is, by loss. The distinction often made is that mourning occurs after the death of a loved one while in melancholia the object of love does not qualify as irretrievably lost.