Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach thi » sach thu, sach tai, sach thieu
hanh dai » hanh tai, hanh dao, vanh dai
cac thoi » cac toi, cac hop, cac tro
ve triet » va trien, su triet
hanh cau » nhanh cau, hang cau, hanh cac
thi hanh » thi thanh
cac tuc » cac toc, cac tu, cac nuoc
cac tac » cac toc, cac bac, cac dac
xa hanh » xa thanh, xa khanh, va hanh
dai ve » dap ve, dau ve, dai va

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 hanh cau hoi. hieu qua ((((cac tuc) or (cac tac))) or (cac thoi)) xa hanh dai ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thi hanh cau hoi. hieu qua ((((cac tuc) OR (cac tac))) OR (cac thoi)) xa hanh dai ve triet.
• Adding a wildcard symbol may retrieve word variants: toc sach thi hanh cau hoi. hieu qua ((((cac tuc) or (cac tac))) or (cac thoi)) xa hanh dai ve triet*.