Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
ty hang » ly hang, ty xang, thi hang
tuc van » thuc van, truc van, tuc va
dau tuc » dau tu, dao tuc, cau truc
van hoi » van hoa, van hoc, van hoe
su sach » so sach
ty lang » tay lang, ty xang, tu lang
vu sach » vu bach, vu khach
cua tre » cua te, cuu tre, cua triet
va dau » va dao
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: ((su sach) or (vu sach)) ((ty lang) OR (ty hang)) van hoi. lieu va dau tuc van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ((ty lang) OR (ty hang)) van hoi. lieu va dau tuc van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) ((ty lang) OR (ty hang)) van hoi. lieu va dau tuc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ((ty lang) OR (ty hang)) van hoi. lieu va dau tuc van hanh vi cua tre*.