Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
hieu ve » hieu va
cac duc » cac du, cao duc, cac dac
va dinh » van dinh, va kinh, va tinh
dinh ve » dinh ket, dinh van
ve cau » ke cau, va cau, ve cac
x hoi » xa hoi, o hoi, x ho

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 (su sach)) ky nang x hoi. ((hieu ve) or (hieu van)) cac duc va dinh ve cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (su sach)) ky nang x hoi. ((hieu ve) OR (hieu van)) cac duc va dinh ve cau tren.
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (su sach)) ky nang x hoi. ((hieu ve) or (hieu van)) cac duc va dinh ve cau tren*.