Perhaps you should try some spelling variations:
hanh sinh » hanh tinh, hanh dinh, hinh sinh
hieu van » hieu va, thien van, lieu va
sinh cua » manh cua, dinh cuu, sinh va
luoc van » luoc can, luoc va, luc van
duc van » duc va, duc tan, duc manh
tu sach » thu sach, su sach, te sach
van cau » van dau, van hau, van chat
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cua tre » cua te, cuu tre, cua triet
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 ty nang ((x hoi) OR (o hoi)). hieu van cau ((luoc van) or (duc van)) hanh sinh cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((x hoi) OR (o hoi)). hieu van cau ((luoc van) OR (duc van)) hanh sinh cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((x hoi) OR (o hoi)). hieu van cau ((luoc van) or (duc van)) hanh sinh cua tre*".