Perhaps you should try some spelling variations:
"thu sach trach nhiem duoc hoc" » "thu sach trac nghiem duoc hoc", "thu sach tranh nhiem duoc hoc", "thu sach truc nhiem duoc hoc", "thu sat trach nhiem duoc hoc", "thu sach trach nghiem duoc hoc", "thu sach trach hiem duoc hoc", "thu sach trach nhiem cuoc hoc", "tu sach trach nhiem duoc hoc", "thuat sach trach nhiem duoc hoc", "thuoc sach trach nhiem duoc hoc", "thu sach trach nhiem quoc hoi"
"te sach trinh nghe du hoc" » "te sach tranh nghe du hoc", "te hanh trinh nghe du hoc", "te sach kinh nghe du hoc", "te sach trinh nghien du hoc", "te sach trinh he du hoc", "te sach trinh nha du hoc", "toc sach trinh nghe du hoc", "te sach trinh nghe duc hoc", "te sach trinh nghe xu hoc", "te sach trinh nghe di hoc", "te sach trinh nghe tu hoc"

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: (("te sach trinh nghe du hoc") or ("thu sach trach nhiem duoc hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("te sach trinh nghe du hoc") OR ("thu sach trach nhiem duoc hoc")).
• Removing quotes may allow a broader search: (( te sach trinh nghe du hoc ) or ( thu sach trach nhiem duoc hoc )).
• Adding a wildcard symbol may retrieve word variants: (("te sach trinh nghe du hoc") or ("thu sach trach nhiem duoc hoc"))*.