Perhaps you should try some spelling variations:
trinh viet » ninh viet, trinh vat
cua triet » cua viet, su triet, va triet
va trinh » van trinh, va tinh, lap trinh
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, dua tren
su sac » su sach, su cac, su xac
sac ky » cac ky, sai ky
du va » dau va, tu va, su 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 sac ky ((nang x) or (nang ma)) hoi. hieu va cac du va trinh viet ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky ((nang x) OR (nang ma)) hoi. hieu va cac du va trinh viet ((cua tre) OR (cua triet)).
• Adding a wildcard symbol may retrieve word variants: su sac ky ((nang x) or (nang ma)) hoi. hieu va cac du va trinh viet ((cua tre) or (cua triet))*.