Perhaps you should try some spelling variations:
"tu mach tiang son - toan tap" » "tu manh giang son - toan tap", "tu mach trung son - toan tap", "tu mach tuan son - toan tap", "tu mach giang son - toan tap", "tu mach tang son - toan tap", "tu mach trang son - toan tap", "tu mach tiang son - toan ban", "tu cach tiang son - toan tap", "tu manh tiang son - toan tap", "tu hach tiang son - toan tap"
"tu mach tich swot - ton giao" » "tu mach tich so - ton giao", "tu mach tich mot - ton giao", "tu mach tich swot - toan giao", "tu mach tich swot - hoc giao", "tu mach tich swot - so giao", "tu cach tich swot - ton giao", "tu manh tich swot - ton giao", "tu hach tich swot - ton giao"

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: (("tu mach tiang son - toan tap") or ("tu mach tich swot - ton giao"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tu mach tiang son - toan tap") OR ("tu mach tich swot - ton giao")).
• Removing quotes may allow a broader search: (( tu mach tiang son - toan tap ) or ( tu mach tich swot - ton giao )).
• Adding a wildcard symbol may retrieve word variants: (("tu mach tiang son - toan tap") or ("tu mach tich swot - ton giao"))*.