Board Thread:Lore Discussion/@comment-13449614-20130726092322/@comment-1940096-20171020155427

Ifnsman wrote: The two Novels, "The Infernal City" and "Lord of Souls", are most definitely canon and both worthy reads.

As for there possibly being any more official books written in the future, this is not known as of yet.

They can only be canon if officially said so by Bethesda.