Perhaps you should try some spelling variations:
thien van » thi van
su triet » su viet, su tien, ve triet
thanh vi » hanh vi, thanh va, thanh ve
hieu van » hieu va, lieu va, hieu ve
sach ty » sach y, sach tu, sach thu
truc va » thuc vat, trung va
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
xang x » nang x
x hoi » xa hoi, o hoi, x ho
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty xang x hoi. ((hieu van) OR (thien van)) cac ((truc va) or (thuc va)) thanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty xang x hoi. ((hieu van) OR (thien van)) cac ((truc va) OR (thuc va)) thanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty xang x hoi. ((hieu van) OR (thien van)) cac ((truc va) or (thuc va)) thanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ty xang x hoi. ((hieu van) OR (thien van)) cac ((truc va) or (thuc va)) thanh vi su triet*.