Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
hanh mau » thanh mau, hanh ma, hanh may
te sach » toc sach
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac

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) or (doc sach)) y nang cao hoi. hieu ve cac duc va ((hanh mau) OR (anh mau)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (doc sach)) y nang cao hoi. hieu ve cac duc va ((hanh mau) OR (anh mau)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (doc sach)) y nang cao hoi. hieu ve cac duc va ((hanh mau) OR (anh mau)) cua tre*".