Test-retest and interobserver reliability of quantitative sensory testing according to the protocol of the German Research Network on Neuropathic Pain (DFNS): a multi-centre study - Geber, C; Klein, T; Azad, S; Birklein, F; Gierthmühlen, J; Huge, V; Lauchart, M; Nitzsche, D; Stengel, M; Valet, M; Baron, R; Maier, C; Tölle, T; Treede, RD (Pain, 2011)