Perhaps you should try some spelling variations:
"so sach bai nghiem dan hoc" » "so sach trai nghiem dan hoc", "so sach thi nghiem dan hoc", "so sach bai nghe dan hoc", "so sach bai nghiem ban hoc", "so sach bai nghiem van hoc", "so sach bai nghiem dau hoc", "so sach dao nghiem dan hoc", "so cac bai nghiem dan hoc", "so sach xa nghiem dan hoc", "so sanh bai nghiem dan hoc", "bo sach bai nghiem dan hoc", "co sach bai nghiem dan hoc", "so sach bai nghiem dan toc", "so sach bai nghiem dai hoc"
"su sac thai nghe xa hoc" » "su rac thai nghe xa hoc", "su sach tham nghe xa hoc", "su toc thai nghe xa hoc", "su sac thai nghe xay hoc", "su sac thai nghe va hoc", "su sac thai nghe xu hoc", "su sach thai nghe xa hoc", "su cac thai nghe xa hoc", "su xac thai nghe xa hoc", "su sac thai nghe xa hoi", "su sac thai nghe xa hoa"

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 bai nghiem dan hoc") or ("su sac thai nghe xa hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("so sach bai nghiem dan hoc") OR ("su sac thai nghe xa hoc")).
• Removing quotes may allow a broader search: (( so sach bai nghiem dan hoc ) or ( su sac thai nghe xa hoc )).
• Adding a wildcard symbol may retrieve word variants: (("so sach bai nghiem dan hoc") or ("su sac thai nghe xa hoc"))*.