Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
cam luc » cam xuc, cau luc
nang xa » nang x, lang xa, nang ma
hieu ve » hieu van
luc van » luoc van, luu van, duc van
hieu va » lieu va, hieu qua
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cam luc van hanh vi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cam luc van hanh vi cua tu*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cam luc van hanh vi cua tu*".