Adding jquery references dynamically

jqueryreference.js

function LoadResources() {
        if (typeof (jQuery) == "undefined") {
            var script = document.createElement("script")
            script.type = "text/javascript";
            script.src = "https://ajax.aspnetcdn.com/ajax/jQuery/jquery-2.0.0.min.js";
            document.getElementsByTagName("head")[0].appendChild(script);
        }
}