Perhaps you should try some spelling variations:
hieu cua » hieu qua, dieu cua, bieu cua
anh thai » anh thi, anh tai, nhanh thai
lang van » dang van, tang van, hoang van
cam duc » cam xuc, cao duc, pham duc
anh hai » lanh hai, manh hai, anh bai
duc ban » duc tan, duc van, dua ban
tu sach » thu sach, su sach, te sach
cua cam » cua cac, cua cay, cua tam
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet

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 ty ((nang xa) or (lang van)) hoi. hieu cua cam duc ban ((anh hai) or (anh thai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (lang van)) hoi. hieu cua cam duc ban ((anh hai) OR (anh thai)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (lang van)) hoi. hieu cua cam duc ban ((anh hai) or (anh thai)) cua tre*.