Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cam luc » cam xuc, cau luc
va hanh » van hanh, va thanh, va danh
sach vu » sach va, sach tu, sach uu
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
vu nang » vuc nang, va nang, vu dang
de cua » te cua, dieu cua
le cua » ly cua

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