Perhaps you should try some spelling variations:
nang ro » nang co, nang ho, nang ra
hieu ve » hieu va, hieu van
sach ky » sac ky, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
nang o » nang co, nang ho, nang x
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 ky) OR (sach y)) ((nang o) or (nang ro)) 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 ky) OR (sach y)) ((nang o) OR (nang ro)) 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 ky) OR (sach y)) ((nang o) or (nang ro)) hoi. hieu ve cac tu va dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach y)) ((nang o) or (nang ro)) hoi. hieu ve cac tu va dan vi cua tre*.