Perhaps you should try some spelling variations:
hinh thai » sinh thai, tinh thai, dinh thi
hanh thai » nhanh thai, hanh tai, anh thai
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
xuc van » duc van, luc van, vuc van
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

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 van ((hanh thai) OR (hinh thai)) 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 van ((hanh thai) OR (hinh thai)) 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 van ((hanh thai) OR (hinh thai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty ((xang xa) or (mang xa)) hoi. hieu van bac xuc van ((hanh thai) OR (hinh thai)) cua tre*.