Perhaps you should try some spelling variations:
tranh mai » tran mai, tranh cai, tranh giai
mai hoang » thai hoang, mai hung, van hoang
vuong dan » huong dan, xuong dan, vuong dao
tuong dan » huong dan, tung dan, xuong dan
doc hieu » toc thieu, hoc thieu, hoc hien
nhan tai » hang tai, van tai, toan tai
doi chi » doi khi

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doi chi) or (doc hieu)) sach - canh tranh mai hoang ((vuong dan) OR (tuong dan)) nhan tai~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doi chi) OR (doc hieu)) sach - canh tranh mai hoang ((vuong dan) OR (tuong dan)) nhan tai.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doi chi) or (doc hieu)) sach - canh tranh mai hoang ((vuong dan) OR (tuong dan)) nhan tai".
• Adding a wildcard symbol may retrieve word variants: ((doi chi) or (doc hieu)) sach - canh tranh mai hoang ((vuong dan) OR (tuong dan)) nhan tai*.