@book{111016,
  address    = {Lima},
  pages      = {30},
  publisher  = {Ministerio de Educación Pública},
  title      = {Cálculo 1},
  url        = {http://www.sil.org/americas/peru/show_work.asp?id=20567},
  year       = {1955},
  country    = {Peru [PE]},
  lgcode     = {Spanish [spa]},
  macro_area = {Eurasia},
  sil_id     = {20567},
  src        = {sil16},
  subject    = {Numbers [Znmb]}
}