Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dieu tra » dieu tri, kiem tra
va hanh » van hanh, va thanh, va danh
so sach » so sanh, bo sach, co sach
hieu ve » hieu va
nang xa » nang x, lang xa, nang ma
sach v » sach va, sach y, sach 2
cac tu » cac thu, cach tu, cac du
v nang » va nang, vu nang, van nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach v nang xa hoi. ((hieu ve) or (hieu van)) cac tu va hanh ((dieu cua) OR (dieu tra)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v nang xa hoi. ((hieu ve) OR (hieu van)) cac tu va hanh ((dieu cua) OR (dieu tra)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach v nang xa hoi. ((hieu ve) or (hieu van)) cac tu va hanh ((dieu cua) OR (dieu tra)) te".
• Adding a wildcard symbol may retrieve word variants: so sach v nang xa hoi. ((hieu ve) or (hieu van)) cac tu va hanh ((dieu cua) OR (dieu tra)) te*.