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