Perhaps you should try some spelling variations:
"cong tac bo vung dat tieu." » "cong tac bo vung mat tieu." (Expand Search), "cong tac bo vung dat viet." (Expand Search), "cong tac bo sung dat tieu." (Expand Search), "cong tac o vung dat tieu." (Expand Search), "cong tac so vung dat tieu." (Expand Search), "cong tac bao vung dat tieu." (Expand Search), "cong bac bo vung dat tieu." (Expand Search), "cong lac bo vung dat tieu." (Expand Search), "dong tac bo vung dat tieu." (Expand Search)
"cong tac bo dung tai lieu." » "cong tac bo dong tai lieu." (Expand Search), "cong tac bo dung doi lieu." (Expand Search), "cong tac bo dung tin lieu." (Expand Search), "cong tac bo duong tai lieu." (Expand Search), "cong tac bao dung tai lieu." (Expand Search), "cong tac bo sung tai lieu." (Expand Search), "cong bac bo dung tai lieu." (Expand Search), "cong lac bo dung tai lieu." (Expand Search), "dong tac bo dung tai lieu." (Expand Search), "cong tac bo dung tai hieu." (Expand Search), "cong tac bo dung tai dieu." (Expand Search)

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: (("cong tac bo vung dat tieu.") OR ("cong tac bo dung tai lieu."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"cong tac bo vung dat tieu.\") OR (\"cong tac bo dung tai lieu.\"))".
• Removing quotes may allow a broader search: (( cong tac bo vung dat tieu. ) OR ( cong tac bo dung tai lieu. )).
• Adding a wildcard symbol may retrieve word variants: (("cong tac bo vung dat tieu.") OR ("cong tac bo dung tai lieu."))*.