Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
dang xay » dang van, van xay
su sach » vu sach
va hanh » van hanh, va danh, ban hanh
dau tuc » dau tu, dao tuc, cau truc
cua tre » cua te, cuu tre, cua triet
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
so sach » so sanh, bo sach, co sach
va cua » va chua, via cua, ca cua
va dau » va dao

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 (so sach)) ky dang xay hoi. lieu va dau tuc ((va hanh) OR (va thanh)) va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ky dang xay hoi. lieu va dau tuc ((va hanh) OR (va thanh)) va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) ky dang xay hoi. lieu va dau tuc ((va hanh) OR (va thanh)) va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) ky dang xay hoi. lieu va dau tuc ((va hanh) OR (va thanh)) va cua tre*.