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