Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
doc sach » hoc sach, toc sach, nuoc sach
ta thanh » tai thanh, va thanh, ha thanh
sach thi » sach thu, sach tai, sach thieu
su triet » su viet, su tien, ve triet
thi hanh » thi thanh
cac toc » cac toi, cac nuoc, cac thoi
hieu va » lieu va, hieu qua
cac tuc » cac tu, cac tac, cac nuoc
ca hoi » cua hoi, xa hoi, co hoi
dai su » dai sua, dai so, dan su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach thi hanh ((ca hoi) OR (cau hoi)). hieu va ((cac tuc) or (cac toc)) ta thanh dai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach thi hanh ((ca hoi) OR (cau hoi)). hieu va ((cac tuc) OR (cac toc)) ta thanh dai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach thi hanh ((ca hoi) OR (cau hoi)). hieu va ((cac tuc) or (cac toc)) ta thanh dai su triet".
• Adding a wildcard symbol may retrieve word variants: doc sach thi hanh ((ca hoi) OR (cau hoi)). hieu va ((cac tuc) or (cac toc)) ta thanh dai su triet*.