Perhaps you should try some spelling variations:
thanh doi » thanh loi, thanh moi, thanh do
cau tren » cu tren, dau tren, ca tren
thanh ve » hanh ve, thanh va, thanh vien
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
cao duc » dao duc, cao suc, giao duc
tu san » thu san, tu ban, tu can
san ky » sang ky, van ky, dan ky
va cao » va cac, va co, 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: tu san ky ((nang ma) OR (tang ma)) hoi. hieu va cao duc va ((thanh ve) or (thanh doi)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu san ky ((nang ma) OR (tang ma)) hoi. hieu va cao duc va ((thanh ve) OR (thanh doi)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu san ky ((nang ma) OR (tang ma)) hoi. hieu va cao duc va ((thanh ve) or (thanh doi)) cau tren".
• Adding a wildcard symbol may retrieve word variants: tu san ky ((nang ma) OR (tang ma)) hoi. hieu va cao duc va ((thanh ve) or (thanh doi)) cau tren*.