Efficacy and tolerability of zinc acetate for treatment of chronic refractory cough: pilot randomised futility trial oleh Aparna Balasubramanian, Janet T. Holbrook, Brendan J. Canning, Loretta G. Que, Mario Castro, Barry J. Make, Linda Rogers, Michael F. Busk, Alexis Rea, Ashley A. McCook-Veal, Jiaxian He, Meredith C. McCormack, Robert A. Wise