J.R.R. Tolkien himself was fond of Blok's minimalistic illustrations, and bought two ("The Battle of Hornburg" and "The Dead Marshes") and was given another ("Dunhov").
Blok's illustrations have been featured as cover art for a Dutch edition of The Lord of the Rings (Spectrum paperback edition in three volumes, published in 1965), in Realms of Tolkien, the Tolkien Calendar 1998, and the forthcoming Official Tolkien Calendar 2011.
Cor Blok's paper "Pictures to accompany a Great Story" was published in Lembas Extra: Proceedings of the 5th Unquendor Lustrum in 2008.
- Interview with Cor Blok on Tolkien Library
- The Ascent of Orodruin, a missing Cor Blok painting, resurfaces at Tolkien Library