Perhaps you should try some spelling variations:
nhanh hai » nhanh thai, thanh hai, nhanh ha
hieu van » hieu va, thien van, lieu va
hanh hai » thanh hai, hang hai, hanh tai
van bac » van ban, van bao, van hac
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
tay hoi » tay ho, tao hoi, tay thai
xay hoi » xa hoi, cay phoi, gay thoi
ky dang » ky nang, ky danh
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 ky dang ((xay hoi) OR (tay hoi)). hieu van bac xuc va ((hanh hai) or (nhanh hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky dang ((xay hoi) OR (tay hoi)). hieu van bac xuc va ((hanh hai) OR (nhanh hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky dang ((xay hoi) OR (tay hoi)). hieu van bac xuc va ((hanh hai) or (nhanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky dang ((xay hoi) OR (tay hoi)). hieu van bac xuc va ((hanh hai) or (nhanh hai)) cua tre*.