^Fixley M, Shen DD, Azarnoff DL (June 1977). "Theophylline bioavailability: a comparison of the oral absorption of a theophylline elixir and two combination theophylline tablets to intravenous aminophylline". The American Review of Respiratory Disease. 115 (6): 955–62. doi:10.1164/arrd.1977.115.6.955 (inactive 1 November 2024). PMID262107.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)