Perhaps you should try some spelling variations:
"tu bach mai chau" » "tu bach moc chau", "tu bach a chau", "tu bach ha chau", "vu bach mai chau", "tu cach mai chau", "tu bac mai chau"
"tu sach doi hoc" » "tu sach hoi hoc", "tu sach moi hoc", "tu sach dao hoc", "thu sach doi hoc", "su sach doi hoc", "te sach doi hoc", "tu sach doi hoac", "tu sach dai hoc"
"tu bach lai chau" » "tu bac dai chau", "tu bach ha chau", "tu mach lac chau", "vu bach lai chau", "tu cach lai chau", "tu bac lai chau"

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 doi hoc") or ((("tu bach mai chau") or ("tu bach lai chau"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu sach doi hoc") OR ((("tu bach mai chau") OR ("tu bach lai chau")))).
• Removing quotes may allow a broader search: (( tu sach doi hoc ) or ((( tu bach mai chau ) or ( tu bach lai chau )))).
• Adding a wildcard symbol may retrieve word variants: (("tu sach doi hoc") or ((("tu bach mai chau") or ("tu bach lai chau"))))*.