Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tham luc » than luc, tham nuoc, tham thuc
nang xa » nang x, lang xa, nang ma
hieu va » lieu va
cuu tre » cua tre, cau tren, cau treo
v nang » va nang, vu nang, van nang
sach v » sach va, sach y, sach 2
va dan » ca dan, va dao, va dap
va dau » va dao
du cuu » tu cuu

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 va) OR (hieu qua)) tham luc ((va dan) or (va dau)) du cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v nang xa hoi. ((hieu va) OR (hieu qua)) tham luc ((va dan) OR (va dau)) du cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach v nang xa hoi. ((hieu va) OR (hieu qua)) tham luc ((va dan) or (va dau)) du cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach v nang xa hoi. ((hieu va) OR (hieu qua)) tham luc ((va dan) or (va dau)) du cuu tre*.