PHP Echoing out specific value from multidimensional array

Question

i store this array into variable $profile

 Array
    (
        [id] => 546645
        [name] => Big Foot
        [first_name] => Big
        [last_name] => Foot
        [email] => blabla@yourmail.com
        [gender] => male
        [picture] => Array
            (
                [is_silhouette] => 
                [url] => www.yourdomain.com/pic.png
            )

        [cover] => Array
            (
                [id] => 75647444
                [offset_y] => 100
                [source] => www.yourdomain.com/roar.png
            )       
    )

How do i get value from [url] and [source]? I wish i can get

www.yourdomain.com/pic.png

www.yourdomain.com/roar.png

I can get the other values with this code, but i dont know how to get value [url] and [source]:

echo $profile['id'].'<br>';
echo $profile['name'].'<br>';
echo $profile['first_name'].'<br>';
echo $profile['last_name'].'<br>';
echo $profile['email'].'<br>';
echo $profile['gender'].'<br>';

Thank you.