Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh ly » khanh ly, hanh ky, hang ly
truc va » thuc va, thuc vat, trung va
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
van hoc » van hoa
van hoi » van hoa, van hoe, van loi
cua tre » cua te, cuu tre, cua triet
y tang » ky tang, 6 tang, 7 tang
ly cua » le cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach y tang ((van hoi) OR (van hoc)). hieu ve cham ((duc va) or (truc va)) hanh ly cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y tang ((van hoi) OR (van hoc)). hieu ve cham ((duc va) OR (truc va)) hanh ly cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y tang ((van hoi) OR (van hoc)). hieu ve cham ((duc va) or (truc va)) hanh ly cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y tang ((van hoi) OR (van hoc)). hieu ve cham ((duc va) or (truc va)) hanh ly cua tre*.