http://police-life.ru/index.php?threads/%D0%A0%D1%83%D1%81%D1%81%D0%BA%D0%B8%D0%B9-%D1%81%D1%82%D0%B8%D0%BB%D1%8C-%D1%80%D1%83%D0%BA%D0%BE%D0%BF%D0%B0%D1%88%D0%BD%D0%BE%D0%B3%D0%BE-%D0%B1%D0%BE%D1%8F.327/page-6

интересное исследование системы Рябко.