Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
duc toan » duc tan, duc hoan, duc thang
duc ton » duc tan
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
anh vi » hanh vi, anh va, anh ve
vi cua » vai cua, di cua
va cao » va cac, va co, va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (thu hoach)) ky tang xa hoi. hieu va cao ((duc toan) OR (duc ton)) anh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thu hoach)) ky tang xa hoi. hieu va cao ((duc toan) OR (duc ton)) anh vi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thu hoach)) ky tang xa hoi. hieu va cao ((duc toan) OR (duc ton)) anh vi cua tre*".