Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
kho tang » cao tang
hieu van » hieu va, thien van, lieu va
luc van » luoc van, luu van, duc van
hanh ve » hanh vi, hanh va, hanh kem
hanh de » hanh kem
van cau » van dau, van hau, van chat
cau luc » cau truc, cau phuc
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 luc van ((hanh de) OR (hanh ve)) 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 luc van ((hanh de) OR (hanh ve)) 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 luc van ((hanh de) OR (hanh ve)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (tu sach)) kho tang xa hoi. hieu van cau luc van ((hanh de) OR (hanh ve)) cua tre*.