Perhaps you should try some spelling variations:
"su sach tranh tai" » "su canh tranh tai", "su sach tranh thai", "su sach trinh tai", "su sach thanh tai", "so sach tranh tai", "vu sach tranh tai"
"tu hoach dinh tri" » "tu hoang dinh tri", "thu hoach dinh tri", "tu hach dinh tri", "quy hoach dinh tri", "tu hoach chinh tri"
"thu van thanh tri" » "thu ban thanh tri", "thu van tuan tri", "thu van thanh tra", "thu van thanh tai", "thu van chinh tri", "thuc van thanh tri", "thuy van thanh tri", "tu van thanh tri"

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 van thanh tri") or ("tu hoach dinh tri"))) or ("su sach tranh tai"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("thu van thanh tri") OR ("tu hoach dinh tri"))) OR ("su sach tranh tai")).
• Removing quotes may allow a broader search: (((( thu van thanh tri ) or ( tu hoach dinh tri ))) or ( su sach tranh tai )).
• Adding a wildcard symbol may retrieve word variants: (((("thu van thanh tri") or ("tu hoach dinh tri"))) or ("su sach tranh tai"))*.