Words . Russ Cochran. pp.  240 , ? .   ^ Les Paul (1988). Little Black Box (video) . http://www.youtube.com/watch?v=3wIgTm2DnPg .   a kind of sound on sound ( i.e. loop music technique utilizing overdub ) machine used on 1988 concert " Les Paul & Friends ". ^ Wheeler, Tom (1992). American Guitars