Perhaps you should try some spelling variations:
sach thi » sach tai, sach thieu, sach tham
cua viet » ca viet, hoa viet, cua vat
sach thu » sach thue, sach thieu, sach tham
hanh ca » hanh cac, hanh cat, hanh cua
cac tuc » cac toc, cac tu, cac tac
cac toi » cac thoi
xa hanh » xa thanh, xa khanh, va hanh
hieu va » lieu va, hieu qua
ca hoi » cau hoi, cua hoi, xa hoi
vi cua » vai cua, di cua

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 thi) or (sach thu)) hanh ca hoi. hieu va ((cac tuc) or (cac toi)) xa hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach thi) OR (sach thu)) hanh ca hoi. hieu va ((cac tuc) OR (cac toi)) xa hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: toc ((sach thi) or (sach thu)) hanh ca hoi. hieu va ((cac tuc) or (cac toi)) xa hanh vi cua viet*.