Perhaps you should try some spelling variations:
"toc sach doanh tri" » "toc sach danh tri", "toc sach tranh tri", "toc cac doanh tri", "toc sach doanh tai", "toc sach doanh tren", "toc sach dinh tri", "hoc sach doanh tri", "doc sach doanh tri", "thuoc sach doanh tri"
"te canh tranh tri" » "te canh trang tri", "te canh thanh tri", "te canh tran tri", "ve canh tranh tri", "te danh tranh tri", "re canh tranh tri"
"toc sach tran thi" » "toc sach tranh thi", "toc sach tren thi", "toc vach tran thi", "hoc sach tran thi", "doc sach tran thi", "thuoc sach tran thi"

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: (("te canh tranh tri") or ((("toc sach doanh tri") or ("toc sach tran thi"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("te canh tranh tri") OR ((("toc sach doanh tri") OR ("toc sach tran thi")))).
• Removing quotes may allow a broader search: (( te canh tranh tri ) or ((( toc sach doanh tri ) or ( toc sach tran thi )))).
• Adding a wildcard symbol may retrieve word variants: (("te canh tranh tri") or ((("toc sach doanh tri") or ("toc sach tran thi"))))*.