From Simon & Schuster, Envy and Gratitude and Other Works 1946-1963 is a perfect introduction to Melanie Klein's modern neuroscientific research.

Melanie Klein's writings, particularly on infant development and psychosis, have been crucial both to theoretical work and to clinical practice. Envy and Gratitude collects her writings from 1946 until her death in 1960, including two papers published posthumously.