Sorensen HT, Pedersen L, Nogard L, Fonager K, Rothman KJ. Does month of birth affect risk of Crohn's disease in childhood and adolescence? BMJ. 2001 Jan 1;323(7318):907.
Henry D, Lim LL, Garcia Rodriguez LA, Perez GS, Carson JL, Griffin M, Savage R, Logan R, Moride Y, Hawkey C, Hill S, Fries JT. Variability in risk of gastrointestinal complications with individual non-steroidal anti-inflammatory drugs: results of a collaborative meta-analysis. BMJ. 1996 Jun 22;312(7046):1563-6.