Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
xuc van » duc van, luc van, vuc van
dau xuc » dau xac, dau xua, dau nuoc
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
van hoc » van hoa
ky dang » ky nang, ky danh
van dau » van dao, phan dau
vi ve » va ve, gi ve, vi he
ve ve » de ve, va ve, ke ve

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 ky dang ((van loi) or (van hoc)). hieu van dau xuc van hanh ((vi ve) OR (ve ve)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky dang ((van loi) OR (van hoc)). hieu van dau xuc van hanh ((vi ve) OR (ve ve)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky dang ((van loi) or (van hoc)). hieu van dau xuc van hanh ((vi ve) OR (ve ve)) triet".
• Adding a wildcard symbol may retrieve word variants: so sach ky dang ((van loi) or (van hoc)). hieu van dau xuc van hanh ((vi ve) OR (ve ve)) triet*.