Perhaps you should try some spelling variations:
te sach » toc sach
thuc va » thuc vat, thuc dan, thuc day
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
tuc va » truc va, tuc xa, duc va
vi cua » vai cua, di cua
ve cam » ve cham, ve cac, va cam
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky nang ((xa hoi) or (o hoi)). hieu ve cam ((tuc va) OR (thuc va)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ((xa hoi) OR (o hoi)). hieu ve cam ((tuc va) OR (thuc va)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ((xa hoi) or (o hoi)). hieu ve cam ((tuc va) OR (thuc va)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ((xa hoi) or (o hoi)). hieu ve cam ((tuc va) OR (thuc va)) hanh vi cua tre*.