function derecha(e) {
if (navigator.appName == 'Netscape' && (e.which == 3 || e.which == 2)){
alert('© A.N.C.R.E.F. www.ancref.org')
return false;
}
else if (navigator.appName == 'Microsoft Internet Explorer' && (event.button == 2)){
alert('© A.N.C.R.E.F. www.ancref.org')
}
}
document.onmousedown=derecha