http://123doc.org/document/3414079-de-an-khao-sat-danh-gia-thuc-trang-cong-nghe-va-de-xuat-cac-giai-phap-ky-thuat-cong-nghe-phat-trien-nhom-cac-san-pham-pin-va-ac-quy-cua-nghanh-cong-ng.htm