Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach thi » sach thu, sach tai, sach thieu
ve triet » su triet
vanh dai » van dai, vanh tai, lanh dao
va trien » va truyen, va thiet, va tuyen
thi hanh » thi thanh
cac tuc » cac tu, cac tac, cac nuoc
cac toc » cac toi, cac nuoc, cac thoi
xa vanh » xa vinh, xa van, xa thanh
hanh ca » hanh cac, hanh cat, hanh cua
ca hoi » cau hoi, cua hoi, xa hoi

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