Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh hai » thanh hai, nhanh hai, hang hai
cac thoi » cac toi, cac hop, cac tro
sach thi » sach thu, sach tai, sach thieu
va triet » va thiet, va trien, ve triet
thi hanh » thi thanh
hieu va » lieu va, hieu qua
xa hanh » xa thanh, xa khanh, va hanh
cac tuc » cac toc, cac tu, cac tac
ca hoi » cau hoi, cua hoi, co hoi
hai va » hai van, thai va, hoi 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 ((ca hoi) OR (xa hoi)). hieu va ((cac tuc) or (cac thoi)) xa hanh hai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thi hanh ((ca hoi) OR (xa hoi)). hieu va ((cac tuc) OR (cac thoi)) xa hanh hai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach thi hanh ((ca hoi) OR (xa hoi)). hieu va ((cac tuc) or (cac thoi)) xa hanh hai va triet".
• Adding a wildcard symbol may retrieve word variants: toc sach thi hanh ((ca hoi) OR (xa hoi)). hieu va ((cac tuc) or (cac thoi)) xa hanh hai va triet*.