Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh vi » hanh vi, thanh va, thanh ve
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
cac toc » cac toi, cac nuoc, cac thoi
cac tac » cac bac, cac dac, cac tai
sach ky » sac ky, sach y, sach ty
vi cua » vai cua, di cua
cua cu » cua chu, cua cau, cua su

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 ((hoang van) or (hang va)) hoi. hieu van ((cac tac) or (cac toc)) ban thanh vi cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((hoang van) OR (hang va)) hoi. hieu van ((cac tac) OR (cac toc)) ban thanh vi cua cu.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((hoang van) or (hang va)) hoi. hieu van ((cac tac) or (cac toc)) ban thanh vi cua cu*.