Perhaps you should try some spelling variations:
thien van » thi van
nang dau » hang dau, xang dau, nang du
van chat » cao chat
danh tai » doanh tai, dinh tai, hanh tai
so triet » su triet, so thiet, bo triet
tu sach » thu sach, su sach, te sach
dau hoi » cau hoi, dai hoi, dan hoi
y nang » ky nang, ly nang, v nang
soc va » hoc va, doc va, goc va
loc va » hoc va, luc va
tai so » tai sao, dai so, tai co

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang dau hoi. thien van chat ((soc va) or (loc va)) danh tai so triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang dau hoi. thien van chat ((soc va) OR (loc va)) danh tai so triet.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang dau hoi. thien van chat ((soc va) or (loc va)) danh tai so triet*.