 Specific valkyries are mentioned on two runestones ; the early 9th century <unk> Runestone in Östergötland , Sweden , and the 10th @-@ century <unk> Runestone on the island of Öland , Sweden , which mentions the valkyrie Þrúðr . On the <unk> Runestone , a kenning is employed that involves a valkyrie riding a wolf as her steed : 
