Kohei Saito's book Karl Marx's Ecosocialism is a detailed examination of the way that Marx's ideas of what we would today call ecology developed and evolved. Kohei Saito engages closely with all of Marx's work - from his published writings, his unpublished (until recently) notebooks, as well as the margin notes and comments that were made in other peoples' writings. Importantly, Kohei Saito also examines the works that Marx himself read to show how Marx was aware of, and increasingly put the question of the "metabolic interaction" between human society and nature into his critique of political economy.
Key to this is Marx's own understanding of the law of value and his theory of alienation, developed earlier in his life. In places this can be a challenging read, but it is important and very rewarding. I recently selected it as one of my reads of 2017 and hope others will engage with Kohei Saito's work.
My longer review of this important book was published in Monthly Review April 2018. You can read it here.