(R)-5-[[2-(6-Amino-9H-purin-9-yl)- 1-methyl ethoxy]methyl]-2,4,6,8- tetraoxa-5-phos phanona nedioic acid, bis(1-methyl ethyl) ester, 5- oxide, (E)-2-butenedioate (1:1)(or)Bis(hydroxymethyl) [[(R)-2-(6- amino-9H-purin-9-yl)-1-methyl ethoxy] methyl]phosphonate, bis(isopropyl carbonate) (ester), fumarate (1:1)(or)9-[(R)-2-Bis[[isopropoxycarbonyl) oxy]methoxy] phosphinyl] methoxy]propyl]adenine fumarate (1:1)