Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu su » hieu sau, tieu su, hieu so
cuu tre » cau tren, cau treo
danh di » danh du, xanh di, danh dien
va danh » va dinh, va dan, va hanh
cham so » cham soc, cham o, ham so
hieu vu » hieu va, hieu ve, dieu vu
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cua triet, dua tren
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
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 v nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v nang xa hoi. ((hieu vu) OR (hieu su)) cham so va danh di ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach v nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: toc sach v nang xa hoi. ((hieu vu) or (hieu su)) cham so va danh di ((cuu tre) OR (cua tre))*.