Pengembangan metode sterilisasi eksplan Gametofit untuk kultur in xitro Lumut Hati Acrolejeunea fertilis (Reinw., Blume & Nees) Schiffn = The Development of Gametophyte sterilization method for Liverworts Acrolejeunea fertilis (Reinw., Blume & Nees) Schiffn In vitro Culture