function switchSubject(newSubj) {
	var elem, div;
	elem = 'thema' + newSubj;
	if (div = document.getElementById(elem)) {
		hideAllSubjects();
		div.style.display = 'block';
 	}
	return false;
}

function hideAllSubjects() {
	var divs, n, i;
	if (divs = document.getElementsByTagName('div')) {
		n = divs.length;
		for (i = 0; i < n; i++) {
			if (divs[i].className == 'themen') {
				divs[i].style.display = 'none';
			}
		} 
	}
}