Perhaps you should try some spelling variations:
"so sach dan y chi đong luc" » "so sach danh y chi đong luc", "so sach dao y chi đong luc", "so sach dat y chi đong luc", "so sanh dan y chi đong luc", "bo sach dan y chi đong luc", "co sach dan y chi đong luc", "so sach dan ky chi đong luc", "so sach dan _ chi đong luc", "so sach day y chi đong luc", "so sach dan ly chi đong luc", "so sach dan a chi đong luc"
"su canh tranh my khi đong luc" » "su canh trinh my khi đong luc", "su canh tran sy khi đong luc", "su canh anh my khi đong luc", "suc canh tranh my khi đong luc", "su can tranh my khi đong luc", "su anh tranh my khi đong luc", "su canh tranh ly khi đong luc", "su canh tranh ky khi đong luc", "su canh tranh my chi 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: (("so sach dan y chi đong luc") or ("su canh tranh my khi đong luc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("so sach dan y chi đong luc") OR ("su canh tranh my khi đong luc")).
• Removing quotes may allow a broader search: (( so sach dan y chi đong luc ) or ( su canh tranh my khi đong luc )).
• Adding a wildcard symbol may retrieve word variants: (("so sach dan y chi đong luc") or ("su canh tranh my khi đong luc"))*.