Perhaps you should try some spelling variations:
anh thuc » am thuc, dan thuc, anh tu
cac thoi » cac toi, cac hop, cac tro
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
nang ho » nang hoc, nang co, tang ho
nang o » nang co, nang ro, nang x
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua

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 ky ((nang o) OR (nang ho)) hoi. hieu ve ((cac thoi) or (anh thuc)) va dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang o) OR (nang ho)) hoi. hieu ve ((cac thoi) OR (anh thuc)) va dan vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang o) OR (nang ho)) hoi. hieu ve ((cac thoi) or (anh thuc)) va dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang o) OR (nang ho)) hoi. hieu ve ((cac thoi) or (anh thuc)) va dan vi cua tre*.