Perhaps you should try some spelling variations:
thuat sach » thuat san
thuat lanh » thuat lap, thuat san
nam thuc » nam thuoc, am thuc, nam thu
va danh » va dinh, va dan, va hanh
xa danh » dia danh, nam danh, van danh
cua tre » cua te, cuu tre, cua triet
hiem he » hiem xe, hieu he, thien he
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
ma hoi » mai hoi, xa hoi, ma hoa
tu cua » hu cua, vu cua
he nam » ha nam, nghe nam

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thuat sach) or (thuat lanh)) ky tang ma hoi. hiem he nam thuc ((xa danh) OR (va danh)) tu cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thuat sach) OR (thuat lanh)) ky tang ma hoi. hiem he nam thuc ((xa danh) OR (va danh)) tu cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thuat sach) or (thuat lanh)) ky tang ma hoi. hiem he nam thuc ((xa danh) OR (va danh)) tu cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thuat sach) or (thuat lanh)) ky tang ma hoi. hiem he nam thuc ((xa danh) OR (va danh)) tu cua tre*.