Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
cach ben » cach bien, bach benh, mach benh
va thanh » gia thanh, ban thanh, va tinh
dang xay » dang van, van xay
vu cach » va cach, ve cach, vu bach
gia muc » gia thuc
gia duc » giao duc, gia thuc, gia dung
mang xa » lang xa, mang may, mang cua
tai va » thai va, mai va, tri va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu cach ben ((mang xa) or (dang xay)) hoi. hieu qua ((gia duc) OR (gia muc)) va thanh tai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu cach ben ((mang xa) OR (dang xay)) hoi. hieu qua ((gia duc) OR (gia muc)) va thanh tai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu cach ben ((mang xa) or (dang xay)) hoi. hieu qua ((gia duc) OR (gia muc)) va thanh tai va thiet".
• Adding a wildcard symbol may retrieve word variants: vu cach ben ((mang xa) or (dang xay)) hoi. hieu qua ((gia duc) OR (gia muc)) va thanh tai va thiet*.