Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
ban thanh » ban hanh, ban hang
hieu van » thien van, lieu va, hieu ve
xuc ban » duc ban, cuc ban, quoc ban
cac xuc » cam xuc, cac nuoc, chat xuc
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
ca viet » va viet, co viet, hoa viet
dai ca » dai cua, dai va, bai ca

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) or (hieu va)) cac xuc ban thanh dai ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. ((hieu van) OR (hieu va)) cac xuc ban thanh dai ca viet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. ((hieu van) or (hieu va)) cac xuc ban thanh dai ca viet*.