Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
than luc » nhan luc, than duc, thanh luu
hieu van » thien van, lieu va, hieu ve
hai cua » thai cua, dai cua, hoi cua
vai cua » dai cua, lai cua, bai cua
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
sach v » sach va, sach y, sach 2
luc va » duc va, tuc va, loc va
v nang » va nang, vu nang, van nang

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