Low for random reals and positive-measure domination
Proceedings of the American Mathematical Society 135 (2007), no. 11, 3703—3709 (electronic).
This is a frequently cited paper containing the sometimes-called “Bjorn’s lemma” (in analogy with Zorn’s lemma?) characterizing LR-reducibility. Stronger results were obtained in a later paper which is still to appear in J. LMS.