Perhaps you should try some spelling variations:
tuan dai » tuan tai, quang dai, tuan dang
toan dai » toan tai, toan bai, toan dam
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
qua cac » cua cac
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
tu san » thu san, tu ban, tu can

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 lang) or (ky dang)) xa hoi. hieu qua cac duc van ((tuan dai) OR (toan dai)) cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu san ((ky lang) OR (ky dang)) xa hoi. hieu qua cac duc van ((tuan dai) OR (toan dai)) cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu san ((ky lang) or (ky dang)) xa hoi. hieu qua cac duc van ((tuan dai) OR (toan dai)) cua vat".
• Adding a wildcard symbol may retrieve word variants: tu san ((ky lang) or (ky dang)) xa hoi. hieu qua cac duc van ((tuan dai) OR (toan dai)) cua vat*.