Asking for help in identifying novels to read.

Per the title. I’m looking for help in identifying some novels around a topic I am interested in. If this is the wrong subreddit, please tell me which one I should go to and I’ll redo this. If someone already has the lists I’m looking for, feel free to provide a link. Anyway, on to the actual ask. I am looking for which books are connected to three characters. Which books star any of the following: Belisarius Cawl; Roboute Guilliman’s return and his appearances post that point; Lion El’Jonson’s return and his appearances post that point. I am especially interested in the books with each of their first appearances (specifically the reemergence for the two primarchs), but if someone can provide me more then I would certainly appreciate it.