“…E65, o2878 [https://doi.org/10.1107/S1600536809043980] 9-[4-Hydroxy-3-(hydroxymethyl)butyl]guanine monohydrate Huang Tang, Feng-Jie Cheng, Nan Li, Yan-Cheng Liu and Zhen-Feng Chen S1. Comment 9-[4-Hydroxy-3-(hydroxymethyl)butyl]guanine (I), known as penciclovir, is very effective for the treatment of herpes simplex virus, varicella zoster virus, Epstein-Barr virus, hepatitis virus and cytomegalovirus (Abdel-Hag et al, 2006;Andrei et al, 2004;Schmid-Wendtner and Korting, 2004;Smith et al, 2001). The crystal lattice is built from molecules of (I) and waters of crystallization (Fig.…”