Pelargonium sidoides root extract for the treatment of acute cough due to lower respiratory tract infection in adults: a feasibility double-blind, placebo-controlled randomised tri... by Willcox, M, Simpson, C, Wilding, S, Stuart, B, Soilemezi, D, Whitehead, A, Morgan, A, Wrixon, E, Zhu, S, Yao, G, Webley, F, Yan, R, Bostock, J, Bell, M, Griffiths, G, Leydon, G, Little, P, Butler, C, Hay, AD, Moore, M