Abrir multiples pestañas URL

<!DOCTYPE html>
<head>
<title>Javascrip YouTube Nº1</title>
</head>
<body>
<script language="javascrip">
function abrirventanas()
{
a = window.open('wwww.infiniter.tk','ininiter','width=410,height=320');
b = window.open('www.youtube.com','youtube','width=410,height=320');
}
</script>
<p><a href="javascript:abrirventanas()" title="Abrir 2 pestañas">Abrir 2 ventanas</a></p>
</body>
</html>