function onSubmit(issn) {
					var f = document.forms['scirus_search'];
					var q;
					var txt;
					var sb;
					
					if (f) {
						q = f.elements['query'];
						
						//search by
						var rb = f.elements['search_by'];

						if (rb) {
							if (rb[0].checked) {
								sb = rb[0].value;
							} else if(rb[1].checked) {
								sb = rb[1].value;
							} 	
						}
						
						//search text						
						txt_field = f.elements['keywords'];
						if (txt_field) {
							txt = txt_field.value;
							var formattedTXT = "";
							var prefix = "";
							if (txt) {
								var keywords = txt.split(" ");
								if (keywords) {
									if (sb == 'au') {
										prefix = 'au:';
									}
									q.value = '(';
									for (i=0; i < keywords.length; i++) {
										formattedTXT += prefix + keywords[i];
										if (i != keywords.length -1) {
											formattedTXT += " OR ";
										}
									}
									q.value+=formattedTXT;
									q.value+=') ';
								}
							}
						}
					}
					
					if (issn) {
						if (q.value != '') {
							q.value += ' AND ';
						}
						if (issn.replace) {
							issn = issn.replace('-', '');
						}
						q.value += '(issn:' + issn + ')';
					}
					
					//deal with option
					f.submit();
				}