Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
vu sach » vu bach, su sach, vu khach
sach ty » sach y, sach tu, sach thu
hanh va » hang va
xua ban » xuat ban, cua ban, qua ban
dau xua » dau cua, dao xuan, dau luan
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ty nang ma hoi. ((hieu van) or (hieu va)) dau xua ban ((hanh vi) or (hanh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ty nang ma hoi. ((hieu van) OR (hieu va)) dau xua ban ((hanh vi) OR (hanh va)) cua tre.
• Adding a wildcard symbol may retrieve word variants: vu sach ty nang ma hoi. ((hieu van) or (hieu va)) dau xua ban ((hanh vi) or (hanh va)) cua tre*.