A series of supplements for RuneQuest, created by Sceaptune Games Ltd.
From the introduction to one of the books:
The Rune Sources series are published under the OGL (Open Gaming License) for RuneQuest™. The series provides supplementary rules and background information for Games Masters and Players. The Rune Sources series includes a new magic system, Petty-Magick, new cults, overviews of individual races and other Games Master aids.