Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh vai » hanh vi, hanh va, hanh tai
ve triet » va trien, su triet
hieu va » lieu va, hieu qua
cac toc » cac toi, cac nuoc, cac thoi
xa hanh » xa thanh, xa khanh, va hanh
cac tuc » cac tu, cac tac, cac nuoc
vai ve » va ve, dai ve, vai 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) OR (thi thanh)) xa hoi. hieu va ((cac tuc) or (cac toc)) xa hanh vai ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((thi hanh) OR (thi thanh)) xa hoi. hieu va ((cac tuc) OR (cac toc)) xa hanh vai ve triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((thi hanh) OR (thi thanh)) xa hoi. hieu va ((cac tuc) or (cac toc)) xa hanh vai ve triet".
• Adding a wildcard symbol may retrieve word variants: toc sach ((thi hanh) OR (thi thanh)) xa hoi. hieu va ((cac tuc) or (cac toc)) xa hanh vai ve triet*.