Perhaps you should try some spelling variations:
"thu sach hoi toc nguoi" » "thu sach hoi con nguoi", "tu sach hoi toc nguoi", "thuat sach hoi toc nguoi", "thuoc sach hoi toc nguoi", "thu sach doi toc nguoi", "thu sach moi toc nguoi", "thu cach thoi toc nguoi", "thu sach hoi hoc nguoi", "thu sach ho toc nguoi", "thu sach hoa toc nguoi"
"loi cach hoc tap nguoi" » "loi cach hoc tay nguoi", "loi cach hoc gap nguoi", "loi cach hoc tac nguoi", "loi cach thuc tap nguoi", "loi cach thoi tap nguoi", "loi dich hoc tap nguoi"
"loi sinh hoc tap nguoi" » "loi sinh hoc tay nguoi", "loi sinh hoc gap nguoi", "loi sinh hoc tac nguoi", "hoi sinh hoc tap nguoi", "noi sinh hoc tap nguoi", "voi sinh hoc tap nguoi"

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: (("thu sach hoi toc nguoi") or ((("loi cach hoc tap nguoi") or ("loi sinh hoc tap nguoi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("thu sach hoi toc nguoi") OR ((("loi cach hoc tap nguoi") OR ("loi sinh hoc tap nguoi")))).
• Removing quotes may allow a broader search: (( thu sach hoi toc nguoi ) or ((( loi cach hoc tap nguoi ) or ( loi sinh hoc tap nguoi )))).
• Adding a wildcard symbol may retrieve word variants: (("thu sach hoi toc nguoi") or ((("loi cach hoc tap nguoi") or ("loi sinh hoc tap nguoi"))))*.