Perhaps you should try some spelling variations:
hieu viec » nhieu viec, hieu ve, sieu viet
cua viet » ca viet, hoa viet, cua vat
hanh vai » hanh vi, hanh va, hanh tai
ban hanh » ban hang
nuoc ban » nuoc san, quoc ban, buoc ban
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
viec cac » vien cac, viec cua, viec lam
vai cua » dai cua, hai cua, lai cua
sach ty » sach y, sach tu, sach thu
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
sac ky » cac ky, sai ky

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 ty) or (sac ky)) ((nang ma) OR (tang ma)) hoi. hieu viec cac nuoc ban hanh vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sac ky)) ((nang ma) OR (tang ma)) hoi. hieu viec cac nuoc ban hanh vai cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sac ky)) ((nang ma) OR (tang ma)) hoi. hieu viec cac nuoc ban hanh vai cua viet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sac ky)) ((nang ma) OR (tang ma)) hoi. hieu viec cac nuoc ban hanh vai cua viet*.