Perhaps you should try some spelling variations:
hoc viet » hoc hien
va tinh » may tinh
ky tang » ky nang, ky dang, kho tang
tang ma » mang may, tang van
qua cac » cua cac
cac tuc » cac toc, cac tu, cac tac
va danh » va dinh, va dan, va hanh
vi hoc » li hoc, va hoc
so sac » so sach, so dac
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: so sac ky tang ma hoi. hieu qua cac tuc ((va danh) or (((va tinh) or (xuan dinh)))) vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sac ky tang ma hoi. hieu qua cac tuc ((va danh) OR (((va tinh) OR (xuan dinh)))) vi hoc viet.
• Adding a wildcard symbol may retrieve word variants: so sac ky tang ma hoi. hieu qua cac tuc ((va danh) or (((va tinh) or (xuan dinh)))) vi hoc viet*.