As of now, you can download for free from Amazon the following two ebooks by Andre Norton:
Book eight of the Witch Word - Estcarp series.
Come. Step through an ancient arch in the Scottish highlands - and into a world beyond all earthly possibilities...
Where fearsome creatures abound and witches rule supreme. Where a sparkling jewel carries a strange and awesome power. Where the terrifying forces of the Dark ravage the countryside.
And where a young Earth woman named Kelsie McBlair holds the key to Witch World's future. Trapped in a bizarre web of science and sorcery, she alone can pierce the savage heart of evil...by confronting the lord of the Dark himself!
Book six of the Witch World - High Hallack Series.
The Waste was stirring and strange forms of the Dark, long quiet, began to wake as Kerovan - whose cloven hoofs marked his kinship with the Old Ones - Journeyed into the Waste on a secret mission, Leaving behind the girl he loved Joisan, however, rode after him, wearing about her neck Kerovan’s gift, a small crystal globe encasing a miniature gryphon. While Kervan strove for answers to the riddles of the Dark, Joisan worked to unlock the power of the crystal gryphon. But only together could they hope to find the ancient Sleeper and defeat the forces of evil.