Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
duc man » duc manh, duc tan, duc mau
dua ban » dia ban, cua ban, qua ban
cao hoc » co hoc, cho hoc, chat hoc
hieu va » lieu va, hieu qua
sach ky » sach y, sach ty, sach kem
va cam » va cham, va cac, va cao
sac ky » cac ky, sai ky
cuc tu » cuc du, luc tu, duc tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) or (sac ky)) nang cao hoc. hieu va cam ((duc man) or (dua ban)) thanh tai cuc tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang cao hoc. hieu va cam ((duc man) OR (dua ban)) thanh tai cuc tu.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang cao hoc. hieu va cam ((duc man) or (dua ban)) thanh tai cuc tu*.