Perhaps you should try some spelling variations:
"su canh tranh thuat lanh kho khan thong" » "su canh trong thuat lanh kho khan thong", "su canh tranh chua lanh kho khan thong", "su canh tranh thai lanh kho khan thong", "su canh tranh thuat lap kho khan thong", "su canh tranh thuat san kho khan thong", "su canh tranh thuat lanh kho khap thong", "su canh tranh thuat lanh kho khau thong", "su canh tranh thuat lanh kho nhan thong", "su canh tranh thuat lanh tho khan thong", "su canh tranh thuat lan kho khan thong", "su canh tranh thuat xanh khoa khan thong", "su canh tranh thuat lanh khoa kham thong", "su canh tranh thuat lanh khoa than thong", "suc canh tranh thuat lanh kho khan thong", "su can tranh thuat lanh kho khan thong", "su anh tranh thuat lanh kho khan thong"
"te sach truc thuc cac khoa hoc thong" » "te cach thuc thuc cac khoa hoc thong", "te sach tren thuc cac khoa hoc thong", "te sach thu thuc cac khoa hoc thong", "te sach truc thuoc cac khoa hoc thong", "te sach thuc thuc cac khoa hoc thong", "te sach truc thuy cac khoa hoc thong", "te sach truc thuc cac khoa hoc thuong", "te sach truc thuc cac khoa hoc trong", "te sach truc thuc cac khoa hoc hong", "te sach truc thuc cach khoa hoc thong", "te sach truc tuc cac khoa hoc thong", "te sach truc phuc cac khoa hoc thong", "te sach truc thuc cac khoan hoc thong", "te sach truc thuc cac khoi hoc thong", "te sach truc thuc dac khoa hoc thong", "te sach truc thuc cac hoa hoc thong", "toc sach truc thuc cac khoa hoc 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: (("su canh tranh thuat lanh kho khan thong") or ("te sach truc thuc cac khoa hoc thong"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("su canh tranh thuat lanh kho khan thong") OR ("te sach truc thuc cac khoa hoc thong")).
• Removing quotes may allow a broader search: (( su canh tranh thuat lanh kho khan thong ) or ( te sach truc thuc cac khoa hoc thong )).
• Adding a wildcard symbol may retrieve word variants: (("su canh tranh thuat lanh kho khan thong") or ("te sach truc thuc cac khoa hoc thong"))*.