$ is not defined even though I'm definitely loading it first

This is my html

<!DOCTYPE html>
<html>
<head>
    <script src='./JS-LIBS/jquery-2.0.0-min.js'></script>
    <script src='./app/app.js'></script>

</head>
<body>
    <h1>HELLO WORLD!</h1>
<h3 id="date">1-1-1697</h3>
<div id="main-content">
    <p>This is my hello world post!</p>
</div>
<div id="comments">
    <h3>Comments</h3>
    <p>This is stupid</p>
</div>
</body>
</html>

The error message in chrome developer tools console is "Uncaught ReferenceError: $ is not defined". This is app.js

$(document).on('ready', function(){
var socket = io.connect('http://localhost:3333');
socket.on('populate', function(data){
    $.each(data, function(index, datum){
        $('h1').text(datum.title);
        $('#date').text(datum.date_published);
        $('#main-content p').text(datum.content);    
    }); 
}); 

});

I'm running it through node.js as a local host on ubuntu if it matters. There does not appear to be an error loading jquery by the way.