display linkedin details in my text fields using php

i have managed to connect with Linkedin APi, so i can get the users details using below code.

$response = $OBJ_linkedin->profile('~:(id,first-name,last-name,picture-url,email-address,phone-numbers)');
if($response['success'] === TRUE) {
$response['linkedin'] = new SimpleXMLElement($response['linkedin']); 

after that i need to display the retrieved details into text fields like this.

<table border="1">
<tr>
<td>Name</td>
<td><?php echo $response['linkedin']->id; ?></td>
</tr>


<tr>
<td>first Name</td>
<td><?php echo $response['linkedin']->first-name; ?></td>
</tr>


<tr>
<td>Email</td>
<td><?php echo $response['linkedin']->email-address; ?></td>
</tr>


</table> 

Id is displaying correctly, but other details are not showing. can anyone help on this. thanks in advance