Perhaps you should try some spelling variations:
thuat lanh » thuat lap, thuat san
te sach » toc sach
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
hieu va » lieu va, hieu qua
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua
cua te » cua tu

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

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