Perhaps you should try some spelling variations:
"cong tac bo tung tai lieu." » "cong tac bo trung tai lieu." (Expand Search), "cong tac bo tuong tai lieu." (Expand Search), "cong tac bo dung tai lieu." (Expand Search), "cong tac bo sung tai lieu." (Expand Search), "cong tac son tung tai lieu." (Expand Search), "cong tac bo trong tai lieu." (Expand Search), "cong bac bo tung tai lieu." (Expand Search), "cong lac bo tung tai lieu." (Expand Search), "cong tac mo tung tai lieu." (Expand Search), "dong tac bo tung tai lieu." (Expand Search)
"cong tac bao dung doi lieu." » "cong tac bao duong doi lieu." (Expand Search), "cong tac bao dang doi lieu." (Expand Search), "cong tac bao dong doi lieu." (Expand Search), "cong tac bao dung doi tieu." (Expand Search), "cong tac bao dung doi dieu." (Expand Search), "cong tac bao dung boi lieu." (Expand Search), "cong tac ban dung doi lieu." (Expand Search), "dong tac bao dung doi lieu." (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 tung tai lieu.") OR ("cong tac bao dung doi lieu."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"cong tac bo tung tai lieu.\") OR (\"cong tac bao dung doi lieu.\"))".
• Removing quotes may allow a broader search: (( cong tac bo tung tai lieu. ) OR ( cong tac bao dung doi lieu. )).
• Adding a wildcard symbol may retrieve word variants: (("cong tac bo tung tai lieu.") OR ("cong tac bao dung doi lieu."))*.