Ter Riet G, Chesley P, Gross AG, Siebeling L, Muggensturm P, Heller N, Umbehr M, Vollenweider D, Yu T, Akl EA, Brewster L, Dekkers OM, M?hlhauser I, Richter B, Singh S, Goodman S, Puhan MA. All that glitters isn't gold: a survey on acknowledgment of limitations in biomedical studies. PLoS One. 2013; 8(11):e73623.