MedlinePlus: Aspirin - Provides information on usage, precautions, side effects and brand names when available. Data provided by government agencies and health-related organizations. - http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a682878.html
MedlinePlus: Aspirin, Butalbital, and Caffeine - Provides information on usage, precautions, side effects and brand names when available. Data provided by government agencies and health-related organizations. - http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a601023.html
Fiorinal With Codeine - Full prescribing information from RxList. - http://www.rxlist.com/cgi/generic/butalcod.htm
Fioricet - Full prescribing information from RxList. - http://www.rxlist.com/cgi/generic/esgic.htm