Retrospective exposure assessment and quality control in an international multi-centre case-control study

H Tinnerberg, P Heikkilä, A Huici-Montagud, F Bernal, A Forni, S Wanders, H Welinder, P Wilhardt, U Strömberg, H Norppa, Lisbeth E. Knudsen, S Bonassi, L Hagmar