Как подключить bootstrap select?

$(document).ready(function() { //  
  $('.selectpicker').selectpicker(); 
});

<!-------- head --------> 
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" /> 
<!-- Latest compiled and minified CSS --> 
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.4/css/bootstrap-select.min.css"> 
<!-------- end head --------> 
 
<select class="selectpicker" multiple> 
  <option>Mustard</option> 
  <option>Ketchup</option> 
  <option>Relish</option> 
</select> 
 
 
<!-------- in the end of the body --------> 
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> 
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script> 
<!-- Latest compiled and minified JavaScript --> 
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.12.4/js/bootstrap-select.min.js"></script> 
<!-------- end of the body -------->