Development and clinical assessment of a heat and moisture exchanger with a multimagnet automatic tracheostoma valve (Provox free Hands HME) for vocal and pulmonary rehabilitation after total laryngectomy. - Hilgers,F.J.; Ackerstaff,A.H.; van As,C.J.; Balm,A.J.; van den Brekel,M.W.; Tan,J.B. (Acta Otolaryngol, 2003)