Systematic reviews of observational studies of Risk of Thrombosis and Bleeding in General and Gynecologic Surgery (ROTBIGGS): introduction and methodology. - Lavikainen, Lauri I.; Guyatt, Gordon H.; Lee, Yung; Couban, Rachel J.; Luomaranta, Anna L.; Sallinen, Ville J.; Kalliala, Ilkka E. J.; Karanicolas, Paul J.; Cartwright, Rufus; Aaltonen, Riikka L.; Ahopelto, Kaisa; Aro, Karoliina M.; et al. (Systematic Reviews, 2021)