Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
hanh hoi » hanh thoi, hanh noi, hanh hoa
kho tang » cao tang
hoi cua » hoi chuc
va hanh » van hanh, va thanh, va danh
truc va » thuc va, thuc vat, trung va
van cau » van dau, van hau, van chat
van hac » van hoc, van ha, van hai
tang xa » trang xa, tang ma, lang xa
tu sach » su sach, te sach, tu cach
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) OR (tu sach)) kho tang xa hoi. hieu ((van cau) or (van hac)) truc va hanh hoi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) kho tang xa hoi. hieu ((van cau) OR (van hac)) truc va hanh hoi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (tu sach)) kho tang xa hoi. hieu ((van cau) or (van hac)) truc va hanh hoi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (tu sach)) kho tang xa hoi. hieu ((van cau) or (van hac)) truc va hanh hoi cua tre*.