function searchByCountry() {
  if (document.getElementById("countrystart").value != '' && document.getElementById("countryziel").value != ''){
    document.country.submit();
  }
}

function searchByRegion() {
  if (document.getElementById("regionstart").value != '' && document.getElementById("regionziel").value != ''){
    document.region.submit();
  }
}

function searchByTerminal() {
  if (document.getElementById("terminalstart").value != '' && document.getElementById("terminalziel").value != ''){
    document.terminals.submit();
  }
}