Perhaps you should try some spelling variations:
sua triet » cua triet, sua tiet, suat thiet
su triet » su viet, su tien, ve triet
duc ngan » duc ngon, duc nhan, luc ngan
hang dai » hoang dai, hang tai, hang dau
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
cam duc » cam xuc, cao duc, pham duc
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, dang xay, lang van
nang ma » tang ma, sang ma, nang cao
van cam » van nam, van lam, van cau

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 ma) or (lang xa)) hoi. hieu van cam duc ngan hang dai ((sua triet) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang ma) OR (lang xa)) hoi. hieu van cam duc ngan hang dai ((sua triet) OR (su triet)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang ma) or (lang xa)) hoi. hieu van cam duc ngan hang dai ((sua triet) or (su triet))*.