http://wiki.rusmedserv.com/index.php/%D0%9F%D0%B5%D1%80%D0%B8%D0%BD%D0%B0%D1%82%D0%B0%D0%BB%D1%8C%D0%BD%D0%B0%D1%8F_%D1%8D%D0%BD%D1%86%D0%B5%D1%84%D0%B0%D0%BB%D0%BE%D0%BF%D0%B0%D1%82%D0%B8%D1%8F_%28%D0%9F%D0%AD%D0%9F%29  вот тут почитайте