Reid, A. H., & Tautenberger, J. K. The origin of the 1918 pandemic influenza virus: A continuing enigma. Journal of General Virology 84, 2285–2292 (2003) ...
Influenza virus is an infectious agent belonging to the virus family Orthomyxoviridae that causes a respiratory tract infection (influenza or 'flu') in vertebrates. There are three main species ...