How are "teaching the teachers" courses in evidence based medicine evaluated? A systematic review oleh Burnand Bernard, Suter Katja, Kunz Regina, Zanrei Gianni, Arvanitis Theodoros N, Horvath Andrea R, Meyerrose Berit, Weinbrenner Susanne, Barnfield Gemma, Thangaratinam Shakila, Kloc Krzysztof, Gabryś Elżbieta, Kaleta Anna, Walczak Jacek, Arditi Chantal, Oude Rengerink Katrien, Harry Gee, Mol Ben WJ, Khan Khalid S