Perhaps you should try some spelling variations:
hieu thien » hieu hien, chieu chien, dieu khien
thien cac » hien cac, thien cau, thieu cac
su triet » su viet, su tien, ve triet
dang xay » dang van, van xay
dinh vai » dinh van, dinh vi, dinh va
va dinh » van dinh, va kinh, va tinh
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cac bao » cach bao, cac bai, cac ban
bao va » bao ve, tao va, ban va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang x) or (dang xay)) hoi. hieu thien cac bao va dinh vai ((cua tre) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang x) OR (dang xay)) hoi. hieu thien cac bao va dinh vai ((cua tre) OR (su triet)).
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang x) or (dang xay)) hoi. hieu thien cac bao va dinh vai ((cua tre) or (su triet))*.