Ch\u01b0\u01a1ng 4 – B\u00e0i 39: V\u1ea5n \u0111\u1ec1 khai th\u00e1c l\u00e3nh th\u1ed5 theo chi\u1ec1u s\u00e2u \u1edf \u0110\u00f4ng Nam B\u1ed9(ti\u1ebfp)<\/a><\/blockquote><\/iframe>