function chkFormular03 () {
  if (document.formular_anfrage.Nachname.value == "") {
    alert("Please insert your name!");
    document.formular_anfrage.Nachname.focus();
    return false;
  }
  if (document.formular_anfrage.Strasse.value == "") {
    alert("Please insert your street!");
    document.formular_anfrage.Strasse.focus();
    return false;
  }
  if (document.formular_anfrage.PLZ.value == "") {
    alert("Please insert your post code!");
    document.formular_anfrage.PLZ.focus();
    return false;
  }
  if (document.formular_anfrage.Ort.value == "") {
    alert("Please insert your town!");
    document.formular_anfrage.Ort.focus();
    return false;
  }
  if (document.formular_anfrage.Land.value == "") {
    alert("Please insert your country!");
    document.formular_anfrage.Land.focus();
    return false;
  }
    if (document.formular_anfrage.email.value  == "") {
    alert("Please insert your e-mail address!");
    document.formular_anfrage.email.focus();
    return false;
  }
  if (document.formular_anfrage.email.value.indexOf("@") == -1) {
    alert("No e-mail address!");
    document.formular_anfrage.email.focus();
    return false;
  }
  if (document.formular_anfrage.Anreise.value == "TT.MM.JJJJ") {
    alert("Please insert an arrival date!");
    document.formular_anfrage.Anreise.focus();
    return false;
  }
  if (document.formular_anfrage.Abreise.value == "TT.MM.JJJJ") {
    alert("Please insert a departure date!");
    document.formular_anfrage.Abreise.focus();
    return false;
  }
  if (document.formular_anfrage.Zimmertyp.value == "Keine_Angabe") {
    alert("Please choose a room type!");
    document.formular_anfrage.Zimmertyp.focus();
    return false;
  }
  if (document.formular_anfrage.Kinder.value > 0) {
   if (document.formular_anfrage.Alter.value == "") {
    alert("Please insert the age of your child/children!");
    document.formular_anfrage.Alter.focus();
    return false; }
  }
}