A step by Step Solution of Rubik's "Magic Cube"
7. Put U corners in place. (contents)
7.c. In two cases out of twelve, there will be no U corners correctly placed, and there will be two pairs of adjacent corners that want to be exchanged. Turn the cube so the exchanges are along the UF and UB edges of the cube, as shown. (hide)
Apply B·LUL'U'·LUL'U'·LUL'U'·B'.