function toggle_contact_how_do_you_know_us() {
	if(document.getElementById("how_do_you_know_us").value == "andere") {
		document.getElementById("how_do_you_know_us_andere").style.display = "block";
		document.getElementById("how_do_you_know_us_andere").style.visibility = "visible";
	} else {
		document.getElementById("how_do_you_know_us_andere").style.display = "none";
		document.getElementById("how_do_you_know_us_andere").style.visibility = "hidden";
	}
}