Perhaps you should try some spelling variations:
"tu canh tranh khong he đong luc" » "tu canh trinh khong he đong luc", "tu canh tran hong he đong luc", "tu canh tranh hang he đong luc", "tu canh tranh khong khi đong luc", "tu canh tranh hong ha đong luc", "tu canh tranh khong _ đong luc", "thu canh tranh khong he đong luc", "tu chanh tranh khong he đong luc", "tu can tranh khong he đong luc"
"su sach trinh cong ha đong luc" » "su sach tranh cong ha đong luc", "su hanh trinh cong ha đong luc", "su sach kinh cong ha đong luc", "su sach trinh dung ha đong luc", "so sach trinh cong ha đong luc", "vu sach trinh cong ha đong luc", "su sach trinh cong hoa đong luc", "su sach trinh dong ha đong luc", "su sach trinh cong tac đong luc"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("su sach trinh cong ha đong luc") or ("tu canh tranh khong he đong luc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach trinh cong ha đong luc") OR ("tu canh tranh khong he đong luc")).
• Removing quotes may allow a broader search: (( su sach trinh cong ha đong luc ) or ( tu canh tranh khong he đong luc )).
• Adding a wildcard symbol may retrieve word variants: (("su sach trinh cong ha đong luc") or ("tu canh tranh khong he đong luc"))*.