Perhaps you should try some spelling variations:
"su sach nguyen thai" » "su hoach nguyen thai", "su quach nguyen thai", "su sach luyen thai", "su sach nguyen thi", "su sach nguyen hai", "su sach nguyen thanh", "vu sach nguyen thai"
"so sach luat tri" » "so sach luan tri", "so sach dat tri", "so hanh luat tri", "so sach luat thi", "so sach luat thai", "so sach quan tri", "so sanh luat tri", "bo sach luat tri", "co sach luat tri"
"su sach van tai" » "su sach han tai", "su sach va tai", "su bach van tai", "vu sach van tai", "su sach von tai", "su sach van tuan"

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: (((("su sach van tai") OR ("so sach luat tri"))) OR ("su sach nguyen thai"))~.
• Removing quotes may allow a broader search: (((( su sach van tai ) or ( so sach luat tri ))) or ( su sach nguyen thai ))~.
• Adding a wildcard symbol may retrieve word variants: (((("su sach van tai") or ("so sach luat tri"))) or ("su sach nguyen thai"))*.