Perhaps you should try some spelling variations:
danh sai » dung sai, danh bat, danh dau
cua tre » cuu tre, cua triet, dua tren
va danh » va dinh, va dan, va hanh
hieu va » lieu va, hieu qua
xac ky » cac ky, bac ky
cac lo » cac lop, cac co, cac bo
nang o » nang co, nang ho, nang ro
sac ky » cac ky, sai ky
cua te » cua tu
o hoc » co hoc, mo hoc, so hoc
lo va » lo van, lao va, ly va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((xac ky) OR (sac ky)) nang o hoc. hieu va cac lo va danh sai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((xac ky) OR (sac ky)) nang o hoc. hieu va cac lo va danh sai ((cua tre) OR (cua te)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((xac ky) OR (sac ky)) nang o hoc. hieu va cac lo va danh sai ((cua tre) or (cua te))".
• Adding a wildcard symbol may retrieve word variants: thu ((xac ky) OR (sac ky)) nang o hoc. hieu va cac lo va danh sai ((cua tre) or (cua te))*.