Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
nang co » nang cao, nang doc, nang noi
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
nang ro » nang ra, nang rong, nang cao
nang ho » nang hoc, tang ho, nang cao
ve cac » va cac, vien cac
cac tu » cac thu, cach tu, cac du
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 ty ((nang ho) or (((nang ro) OR (nang co)))) hoi. hieu ve cac tu va dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang ho) OR (((nang ro) OR (nang co)))) hoi. hieu ve cac tu va dan vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang ho) or (((nang ro) OR (nang co)))) hoi. hieu ve cac tu va dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang ho) or (((nang ro) OR (nang co)))) hoi. hieu ve cac tu va dan vi cua tre*.