Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
lang van » dang van, tang van, hoang van
dai cuu » dai cua, dai huu
va vanh » va van, va danh, va hanh
cao duc » dao duc, cao suc, giao duc
qua cao » qua cac, qua ca, qua cai
lang ha » long ha
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
cuu tre » cua tre, cau tren, cau treo

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 ky) OR (sach ty)) ((lang van) or (lang ha)) hoi. hieu qua cao duc va vanh dai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach ty)) ((lang van) OR (lang ha)) hoi. hieu qua cao duc va vanh dai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) OR (sach ty)) ((lang van) or (lang ha)) hoi. hieu qua cao duc va vanh dai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) OR (sach ty)) ((lang van) or (lang ha)) hoi. hieu qua cao duc va vanh dai cuu tre*.