Perhaps you should try some spelling variations:
nang cau » nang cao, hang cau, nang dau
hieu van » hieu va, thien van, hieu ve
cam thuc » am thuc, nam thuc, cam thu
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
luy tre » luyen tre
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
vi luy » vi lua, vi luu

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sac ky nang cau hoi. ((hieu van) or (lieu va)) cam thuc ((va hanh) OR (va danh)) vi luy tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky nang cau hoi. ((hieu van) OR (lieu va)) cam thuc ((va hanh) OR (va danh)) vi luy tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky nang cau hoi. ((hieu van) or (lieu va)) cam thuc ((va hanh) OR (va danh)) vi luy tre".
• Adding a wildcard symbol may retrieve word variants: te sac ky nang cau hoi. ((hieu van) or (lieu va)) cam thuc ((va hanh) OR (va danh)) vi luy tre*.