Perhaps you should try some spelling variations:
thanh lai » thanh hai, thanh lap, thanh loi
chat dua » chat cua, chat lua, chay dua
dua ban » dia ban, cua ban, qua ban
ve chat » va chat, van chat
sach ky » sac ky, sach ty, sach kem
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
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: toc ((sach ky) or (sach y)) nang ma hoa. hieu ve chat dua ban ((thanh lai) or (thanh san)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ky) OR (sach y)) nang ma hoa. hieu ve chat dua ban ((thanh lai) OR (thanh san)) cua tre.
• Adding a wildcard symbol may retrieve word variants: toc ((sach ky) or (sach y)) nang ma hoa. hieu ve chat dua ban ((thanh lai) or (thanh san)) cua tre*.