Perhaps you should try some spelling variations:
"thu sach pham thuc hanh kho khan thong" » "thu sach pham thuc hanh kho khap thong", "thu sach pham thuc hanh kho khau thong", "thu sach pham thuc hanh kho nhan thong", "thu sach tham thuc hanh kho khan thong", "thu sach phat thuc hanh kho khan thong", "thu sach phap thuc hanh kho khan thong", "thu sach pham chuc hanh kho khan thong", "thu sach nham thuc hanh kho khan thong", "tu sach pham thuc hanh kho khan thong", "thuat sach pham thuc hanh kho khan thong", "thuoc sach pham thuc hanh kho khan thong", "thu sach pham thuc hanh khu khan thong", "thu sach pham thuc hang khoa khan thong", "thu sach pham thuc hanh theo khan thong", "thu sach pham thuc hanh khoa kham thong", "thu sach pham thuc hanh khoa than thong"
"te sach trinh tu cac hoa he thong" » "te sach tranh tu cac hoa he thong", "te hanh trinh tu cac hoa he thong", "te sach kinh tu cac hoa he thong", "te sach trinh ky cac hoa he thong", "te sach trinh do cac hoa he thong", "toc sach trinh tu cac hoa he thong", "te sach trinh tu cac hoat he thong", "te sach trinh tu cac khoa he thong", "te sach trinh tu cau hoa he thong"

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 pham thuc hanh kho khan thong") or ("te sach trinh tu cac hoa he thong"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("thu sach pham thuc hanh kho khan thong") OR ("te sach trinh tu cac hoa he thong")).
• Removing quotes may allow a broader search: (( thu sach pham thuc hanh kho khan thong ) or ( te sach trinh tu cac hoa he thong )).
• Adding a wildcard symbol may retrieve word variants: (("thu sach pham thuc hanh kho khan thong") or ("te sach trinh tu cac hoa he thong"))*.