@book{Laack2002,
  author    = {Laack, Walter van},
  title     = {A better history of our world / Vol. 2. Life},
  publisher = {van Laack},
  address   = {Aachen},
  isbn      = {978-3-8311-2597-5},
  pages     = {236 S.},
  year      = {2002},
  language  = {en}
}
@book{Laack2001,
  author    = {Laack, Walter van},
  title     = {A better history of our world / Vol. 1. The universe},
  publisher = {van Laack},
  address   = {Aachen},
  isbn      = {978-3-8311-1490-0},
  pages     = {188 S.},
  year      = {2001},
  language  = {en}
}