Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dieu cua » dieu tra
van hanh » van thanh, ban hanh, van anh
cam luc » cam xuc, cau luc
luc van » luoc van, luu van, duc van
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma
de cua » le cua, te 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 ky nang xa hoi. ((hieu ve) or (hieu va)) cam luc van hanh ((de cua) OR (dieu cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. ((hieu ve) OR (hieu va)) cam luc van hanh ((de cua) OR (dieu cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang xa hoi. ((hieu ve) or (hieu va)) cam luc van hanh ((de cua) OR (dieu cua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. ((hieu ve) or (hieu va)) cam luc van hanh ((de cua) OR (dieu cua)) tre*.