Perhaps you should try some spelling variations:
"su sach quan tri" » "su sach quang tri", "su sach luan tri", "su tac quan tri", "so sach quan tri", "vu sach quan tri"
"su sach nang thi" » "su cach mang thi", "su sach dung thi", "su sach danh thi", "su sach dang thi", "su sach tang thi", "su sach nang tai", "so sach nang thi", "vu sach nang thi"
"bo sach nang tri" » "bo cach mang tri", "bo sach dung tri", "bo sach danh tri", "bo sach nang tai", "bo sach lang tri", "bo sach quang tri", "co sach nang tri", "hoc sach nang tri"

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 quan tri") or ((("su sach nang thi") or ("bo sach nang tri"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su sach quan tri") OR ((("su sach nang thi") OR ("bo sach nang tri")))).
• Removing quotes may allow a broader search: (( su sach quan tri ) or ((( su sach nang thi ) or ( bo sach nang tri )))).
• Adding a wildcard symbol may retrieve word variants: (("su sach quan tri") or ((("su sach nang thi") or ("bo sach nang tri"))))*.