T?i ?ây ngoài s? ?a d?ng v? nh?ng s?n ph?m trò ch?i thì vi?c ??ng ký, ??ng nh?p K8 luôn ? m?c ?? an toàn, ??m b?o cho ng??i ch?i luôn ? m?c tuy?t ??i. DV1 contributed for the scheduling in the manuscript, done the literature evaluation, wrote the main draft of the manuscript; VR planned in the manuscript and supplied the essential evaluati