Perhaps you should try some spelling variations:
"so sach quoc phong" » "so sach quoc hung", "so sach quoc vuong", "so sach quoc cuong", "so sach duoc phong", "so sach nuoc phong", "so quach quoc phong", "so sanh quoc phong", "bo sach quoc phong", "co sach quoc phong"
"vu hoach hoi khoa" » "vu hoc hoi khoa", "vu hoach ha khoa", "vu sach hoi khoa", "quy hoach hoi khoa", "thu hoach hoi khoa", "qui hoach hoi khoa", "vu hoach hoc khoa", "vu hoach noi khoa", "vu hoach tai khoa"
"tu sach dao do" » "tu lanh dao do", "thu sach dao do", "su sach dao do", "te sach dao do", "tu sach dao o", "tu sach dao ho", "tu sach do do"

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: (("tu sach dao do") or ((("so sach quoc phong") or ("vu hoach hoi khoa"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu sach dao do") OR ((("so sach quoc phong") OR ("vu hoach hoi khoa")))).
• Removing quotes may allow a broader search: (( tu sach dao do ) or ((( so sach quoc phong ) or ( vu hoach hoi khoa )))).
• Adding a wildcard symbol may retrieve word variants: (("tu sach dao do") or ((("so sach quoc phong") or ("vu hoach hoi khoa"))))*.