Google SpreadSheetsをGoogle APIs Client Library for PHP 1.1.6で叩くための準備 ref: http://qiita.com/sakadon/items/84593201b8801a8a3a8a

certkey.json

{
  "private_key_id": "################",
  "private_key": "-----BEGIN PRIVATE KEY-----\#####################################################################################################-----END PRIVATE KEY-----\n",
  "client_email": "########@developer.gserviceaccount.com",
  "client_id": "#########gsa.apps.googleusercontent.com",
  "type": "service_account"
}

test.php

// load Google APIs Client Library for PHP ver 1.1.6
require_once "/unko/Google/autoload.php";

$client = new Google_Client();
$client->setApplicationName("getSpreadsheet");

$credentials = $client->loadServiceAccountJson("/unko/.secret/certkey.json", array(
    Google_Service_Drive::DRIVE
));
$client->setAssertionCredentials($credentials);
$client->getAuth()->refreshTokenWithAssertion();

$accessTokenJson = $client->getAccessToken();
$accessToken = json_decode($accessTokenJson)->access_token;

// GET spreadsheets
$sheet_id = "##########################################";
$request = new Google_Http_Request(
    "https://spreadsheets.google.com/feeds/worksheets/{$sheet_id}/private/full?alt=json",
    "GET",
    array("Authorization" => "Bearer {$accessToken}")
);
$curl = new Google_IO_Curl($client);
$res = $curl->executeRequest($request);

// データ
$data = json_decode($res[0]);

//print_r( $data['feed']['entry'] )

foreach ($data->feed->entry as $sheets) {
    if( $sheets->title->{"\$t"} == 'シート名は直接指定' ) {

        foreach ($sheets->link as $links) {
            if( $links->rel == 'http://schemas.google.com/spreadsheets/2006#listfeed' ){
                $listfeed = $links->href;
                echo '$listfeed: '.$listfeed;
            }
            if( $links->rel == 'http://schemas.google.com/spreadsheets/2006#cellsfeed' ){
                $cellsfeed = $links->href;
                echo '$cellsfeed: '.$cellsfeed;
            }
        }
    }
}