Perhaps you should try some spelling variations:
cau triet » cau trieu, su triet, cua triet
cau treo » cau theo, cau tren, cau trieu
van pham » san pham, van phan, van phat
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, mang xa
tu sach » thu sach, su sach, te sach
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va

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 xa) or (nang ma)) hoi. hieu van pham duc va dan vi ((cau treo) or (cau triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu van pham duc va dan vi ((cau treo) OR (cau triet)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. hieu van pham duc va dan vi ((cau treo) or (cau triet))*.