Perhaps you should try some spelling variations:
te sach » toc sach
luc van » luoc van, luu van, duc van
cau luc » cau truc, cau phuc
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
ty hang » ly hang, ty xang, thi hang
cua tre » cua te, cuu tre, cua triet
ve cau » ke cau, va cau, ve cac
anh vi » hanh vi, anh ve, anh vu
anh va » hanh va
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty hang ((o hoi) OR (o hoc)). hieu ve cau luc van ((anh vi) or (anh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty hang ((o hoi) OR (o hoc)). hieu ve cau luc van ((anh vi) OR (anh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty hang ((o hoi) OR (o hoc)). hieu ve cau luc van ((anh vi) or (anh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty hang ((o hoi) OR (o hoc)). hieu ve cau luc van ((anh vi) or (anh va)) cua tre*.