Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
nam tuc » nam thuc, nam truc, nam tu
hang di » hang doi, hang vi, hang dien
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, tuc xa

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) or (thu hoach)) ky nang ma hoi. hieu van nam tuc va ((hanh vi) or (hang di)) cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu hoach)) ky nang ma hoi. hieu van nam tuc va ((hanh vi) OR (hang di)) cua viet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu hoach)) ky nang ma hoi. hieu van nam tuc va ((hanh vi) or (hang di)) cua viet*.