Perhaps you should try some spelling variations:
"tu canh tranh tren" » "tu canh trinh tren", "tu canh tran tren", "tu canh tranh trong", "thu canh tranh tren", "tu chanh tranh tren", "tu can tranh tren"
"tu sach dau tren" » "tu sach dao tren", "tu sach dat tren", "tu sach mau tren", "tu sach dau tieng", "tu sach dau trong", "thu sach dau tren", "su sach dau tren", "te sach dau tren"
"tu sach dau tien" » "tu sach dao tien", "tu sach dat tien", "tu sach mau tien", "tu sach van tien", "thu sach dau tien", "su sach dau tien", "te sach dau tien"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("tu canh tranh tren") or ((("tu sach dau tren") or ("tu sach dau tien"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu canh tranh tren") OR ((("tu sach dau tren") OR ("tu sach dau tien")))).
• Removing quotes may allow a broader search: (( tu canh tranh tren ) or ((( tu sach dau tren ) or ( tu sach dau tien )))).
• Adding a wildcard symbol may retrieve word variants: (("tu canh tranh tren") or ((("tu sach dau tren") or ("tu sach dau tien"))))*.