Ie, I am assuming that they are both ultimately deriviative of PIE *sem-/*som-.
So, how are they derived from this, in terms of morphemes, and their meanings?
I have skimmed through both Ringe and Beekes. Excellent books, that I want to go through properly in the near future, but this question has been bugging me - the etymology at a later point in time was asked as part of a paper, and it annoyed me that I could not give a full explanation.
Would these two books be the best for getting a coherent understanding of theorised derivation processes and, in particular, PIE verbs? I've had some trouble wrapping my head around what can be said to be diachronic and what synchronic at times, fex when what processes were actively occurring, how salient the underlying analysis of x was, and the like.
Feel free to add sources/references/bibliographical details, I've read around a lot of related literature but not a lot on PIE qua PIE.