Ok, I set up this thread for any who are interested in compiling all the little nods and references within the Horus Heresy series to outside influences. These are normally in reference to Old Earth (circa M2) and its cultures, artworks, literature.

Three of my favorites (that i can remember offhand) are:

- The nods to old cities such as L'undone (think this was how it was spelt).
- The override code in Deliverence lost is "Peta Orpheus Epsilon" POE. as in Edgar.
- The starship Heart of Gold was "improbably destroyed" in a space battle in Fulgrim.

Please post any other you can remember. I beleive there are quite a few, especially with reference to works of literature etc.