Perhaps you should try some spelling variations:
nguyen tai » nguyen thai, nguyen thi, nguyen tac
quyen tai » xuyen tai, truyen tai, luyen thi
cong cong » cong dong, trong cong, dang cong
dung cong » dung trong
cac khu » cac thu, cac khoi, cac kieu
ban ly » ban lay, bang ly, ban le
y thu » ly thu, ky thu, y thuc
ly y » ly ky

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((quyen tai) OR (nguyen tai)) cac khu đe co ban ly y thu ((cong cong) OR (dung cong))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((quyen tai) OR (nguyen tai)) cac khu đe co ban ly y thu ((cong cong) or (dung cong))~".
• Adding a wildcard symbol may retrieve word variants: ((quyen tai) OR (nguyen tai)) cac khu đe co ban ly y thu ((cong cong) or (dung cong))*.