Tiotropium in combination with placebo, salmeterol, or fluticasone-salmeterol for treatment of chronic obstructive pulmonary disease: a randomized trial.Shawn D. Aaron, Mark Fitzgerald, David G. McCormack et al.|PubMed|2007Cited by 653
A Comparison of Magnesium Sulfate and Nimodipine for the Prevention of EclampsiaMichael A. Belfort, George R. Saade, John Anthony|New England Journal of Medicine|2003Cited by 280