Pickering LK, Rutherford I. Effect of concentration and time upon inactivation of tobramycin, gentamicin, netilmicin, and amikacin by azlocillin, carbenicillin, mecillinam, mezlocillin, and piperacillin. J Pharmacol Exp Ther. 1981; 217:345–9.[PubMed 6453219]