- implode: documentation ( source)
<?php
$authors = array('Johnny', 'Jim', 'Jack');
$data = array();
for ($id=0; $id<10; $id++)
{
$data[$id] = array(
'id' => $id,
'title' => 'Title',
'source' => 'Source',
'year' => '2013',
'type' => 'Type',
'authors' => implode(', ', $authors)
);
}