Perhaps you should try some spelling variations:
thuat lanh » thuat lap, thuat san
vanh dai » van dai, vanh tai, lanh dao
hieu va » lieu va, hieu qua
va vanh » va van, va danh, va hanh
cac luc » cau luc, coc luc, cac nuoc
tu sach » thu sach, su sach, te sach
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
cua tuc » cua duc, cua thuoc, luat tuc
ma hoi » mai hoi, xa hoi, ma hoa
luc va » duc va, tuc va, loc va
cua tu » cua su, cua cu, cua te

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

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