Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh dai » hanh tai, hanh dao, vanh dai
ve triet » va trien, su triet
da nang » cam nang, kha nang, cao nang
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
luc va » duc va, tuc va
loc va » hoc va
v nang » va nang, vu nang, van nang
dai ve » dap ve, dau ve, dai 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 ((v nang) or (da nang)) cao hoi. hieu ve cham ((luc va) or (loc va)) hanh dai ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v nang) OR (da nang)) cao hoi. hieu ve cham ((luc va) OR (loc va)) hanh dai ve triet.
• Adding a wildcard symbol may retrieve word variants: toc sach ((v nang) or (da nang)) cao hoi. hieu ve cham ((luc va) or (loc va)) hanh dai ve triet*.