function chkFormular() {
  if (document.Formular.Name.value == "") {
    alert("Please provide your full name!");
    document.Formular.Name.focus();
    return false;
  }
  if (document.Formular.Email.value == "") {
    alert("Please provide us your email address!");
    document.Formular.Email.focus();
    return false;
  }

  if (document.Formular.EmailBest.value == "") {
    alert("Please confirm your email address!");
    document.Formular.EmailBest.focus();
    return false;
  }
   if (document.Formular.Telefon.value == "") {
    alert("Bitte geben Sie eine vollständige Telefonnummer ohne Buchstaben oder Sonderzeichen ein!");
        alert("Please enter a full phone number without characters or special signs");
    document.Formular.Telefon.focus();
    return false;
  }
   if (document.Formular.Teilnehmer.value == "") {
    alert("Please enter the desired number of participants!");
    document.Formular.Teilnehmer.focus();
    return false;
  }
 if (document.Formular.Rom_von.value == "") {
    alert("Please tell us from which date on you intend to stay in Rome!");
    document.Formular.Rom_von.focus();
    return false;
  }
  if (document.Formular.Rom_bis.value == "") {
    alert("Please tell us until which date on you intend to stay in Rome!");
    document.Formular.Rom_bis.focus();
    return false;
  }
}