Perhaps you should try some spelling variations:
thach duc » thach thuc, than duc, thinh duc
hieu van » thien van, lieu va, hieu ve
thanh vi » hanh vi, thanh va, thanh ve
va thanh » gia thanh, ban thanh, va tinh
hieu va » lieu va, hieu qua
su sach » so sach, vu sach
sach vu » sach va, sach tu, sach uu
cao hoc » co hoc, cho hoc, chat hoc
cao hoi » cau hoi, co hoi, tao hoi
vu nang » vuc nang, va nang, vu dang
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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 vu nang ((cao hoi) OR (cao hoc)). ((hieu van) or (hieu va)) thach duc va thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach vu nang ((cao hoi) OR (cao hoc)). ((hieu van) OR (hieu va)) thach duc va thanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach vu nang ((cao hoi) OR (cao hoc)). ((hieu van) or (hieu va)) thach duc va thanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach vu nang ((cao hoi) OR (cao hoc)). ((hieu van) or (hieu va)) thach duc va thanh vi cua tre*.