Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, anh thai
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
su sach » so sach, vu sach
van bac » van ban, van bao, van hac
sach ty » sach y, sach tu, sach thu
mang xa » lang xa, mang may, dang xay
xang xa » lang xa, ang xa, dang xay
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, luc 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 sach ty ((xang xa) or (mang xa)) hoi. hieu van bac xuc va ((hanh thai) OR (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((xang xa) OR (mang xa)) hoi. hieu van bac xuc va ((hanh thai) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((xang xa) or (mang xa)) hoi. hieu van bac xuc va ((hanh thai) OR (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((xang xa) or (mang xa)) hoi. hieu van bac xuc va ((hanh thai) OR (hanh tai)) cua tre*.