Jill P. Karpel, E. Neil Schacter, David Levey, Peter Spiro, Thomas Aldrich, Shailendra S. Menjoge, Theodore J. Witek, Christopher Fanta,
A Comparison of Ipratropium and Albuterol vs Albuterol Alone for the Treatment of Acute Asthma Chest. ,vol. 110, pp. 611- 616 ,(1996) ,
10.1378/CHEST.110.3.611