Loewe,M.;Blacker,C.(1981).Oracles and Divination.London:George Allen & Unwin.p.130."'Vardlokkur'...is related to the Scots dialect word 'warlock', wizard, and the meaning is thought to relate to the power to shut in or enclose""
Oxford English Dictionary, (online) 2nd Edition (1989): "ON. varðlokkur wk. fem. pl. ... incantation, suggested already in Johnson, is too rare (? occurring once), with regard to the late appearance of the -k forms, to be considered."
Thomas Thomson, A History of the Scottish People from the Earliest Times (1896), page 286: "Where one man suffered as a warlock, ten women at least were executed as witches."
Journal of Jurisprudence and Scottish Law Magazine (1891), Execution of the Judgment of Death, page 397: "We read (Law's Memor. Pref. lix.) that 'one John Brugh, a notorious warlock (wizard) in the parochin of Fossoquhy, by the space of thirty-six years, was worried at a stake and burned, 1643.'"