https-web-archive-org-web-20230322070724-http-giasuglory-edu-vn-ly-luan-chinh-tri-triet-hoc-mac-lenin-hoi-phan-tich-noi-dung-y-nghia-phuong-phap-luan-dinh-nghia-vat-chat-cua-lenin-56
https-web-archive-org-web-20230322070724-http-giasuglory-edu-vn-ly-luan-chinh-tri-triet-hoc-mac-lenin-hoi-phan-tich-noi-dung-y-nghia-phuong-phap-luan-dinh-nghia-vat-chat-cua-lenin-56