@article{MikelskisHornSeifert1999,
  author    = {Mikelskis, Helmut and Horn, Martin Erik and Seifert, Silke},
  title     = {Learning physics aided by computer simulations "Optics Phenomena"},
  year      = {1999},
  language  = {en}
}
@article{MikelskisSeifertRoesler1999,
  author    = {Mikelskis, Helmut and Seifert, Silke and Roesler, Frank},
  title     = {Optik lernen mit der Simulationssoftware phenOpt},
  issn      = {0025-5866},
  year      = {1999},
  language  = {de}
}