function performSearch() {
	var colsearch = document.getElementById('colsearch').value;
	if (colsearch=='true') {
		var searchTerm = document.getElementById('search_term').value;
		if (searchTerm=='' || searchTerm=='Enter Keywords') {
			alert('Please enter a valid search term');
			document.getElementById('search_term').focus();
		} else {
			window.location='http://librarysearch.rhul.ac.uk/Summon/Search?lookfor='+searchTerm;
		}
		
		return false;
	} else {
		return true;
	}
}