Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
toc sach » hoc sach, doc sach, thuoc sach
va hanh » van hanh, va thanh, va danh
cua lao » cu lao, ca lao, cua dao
hieu va » lieu va, hieu qua
toc sac » toc san, hoc sach, doc sach
hieu ve » hieu van
nang xa » nang x, lang xa, nang ma
lao va » tao va, cao va, bao va
vi cua » vai cua, di 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 sac) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cua lao va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sac) OR (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cua lao va hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sac) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cua lao va hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: ((toc sac) or (toc sach)) ky nang xa hoi. ((hieu ve) OR (hieu va)) cua lao va hanh vi cua viet*.