Perhaps you should try some spelling variations:
van hanh » van thanh, van anh, van ban
ban hanh » ban hang
dieu cua » dieu tra
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
tu san » thu san, tu ban, tu can
san ky » sang ky, van ky, dan ky
qua ca » qua cac, qua cua, qua cai
ca duc » cao duc, cua duc, ca dua
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: tu san ky lang xa hoi. hieu qua ca duc ((van hanh) OR (ban hanh)) ((de cua) or (dieu cua)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu san ky lang xa hoi. hieu qua ca duc ((van hanh) OR (ban hanh)) ((de cua) OR (dieu cua)) viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu san ky lang xa hoi. hieu qua ca duc ((van hanh) OR (ban hanh)) ((de cua) or (dieu cua)) viet*".