Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cau treo » cau theo, cau tren, cau triet
nang xa » nang x, lang xa, nang ma
va nang » van nang, da nang, cam nang
hieu vu » hieu va, hieu ve, dieu vu
hieu su » hieu sau, tieu su, hieu so
sach va » sach xa, sach ha, sach dao
cham so » cham soc, cham o, ham so
va danh » va dinh, va dan, va hanh
danh di » danh du, xanh di, danh dien
cuu tre » cua tre, cau tren
so va » so van, so vat, su va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach va nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di ((cuu tre) OR (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach va nang xa hoi. ((hieu vu) OR (hieu su)) cham so va danh di ((cuu tre) OR (cau treo)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach va nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di ((cuu tre) OR (cau treo))".
• Adding a wildcard symbol may retrieve word variants: toc sach va nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di ((cuu tre) OR (cau treo))*.