Perhaps you should try some spelling variations:
"dong tac bo sung tai lieu." » "dong bac bo sung tai lieu." (Expand Search), "dong tay bo sung tai lieu." (Expand Search), "dong cac bo sung tai lieu." (Expand Search), "dong tac bo dung tai lieu." (Expand Search), "dong tac bo vung tay lieu." (Expand Search), "dong tac bo sung nam lieu." (Expand Search), "dong tac bao sung tai lieu." (Expand Search), "dong lac bo sung tai lieu." (Expand Search)
"cong tac bo dong tai lieu." » "cong tac bo dong thu lieu." (Expand Search), "cong tac bo dong bao lieu." (Expand Search), "cong tac bao dong tai lieu." (Expand Search), "cong tac bo duong tai lieu." (Expand Search), "cong tac o dong tai lieu." (Expand Search), "cong bac bo dong tai lieu." (Expand Search), "cong lac bo dong tai 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: (("dong tac bo sung tai lieu.") OR ("cong tac bo dong tai lieu."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"dong tac bo sung tai lieu.\") OR (\"cong tac bo dong tai lieu.\"))".
• Removing quotes may allow a broader search: (( dong tac bo sung tai lieu. ) OR ( cong tac bo dong tai lieu. )).
• Adding a wildcard symbol may retrieve word variants: (("dong tac bo sung tai lieu.") OR ("cong tac bo dong tai lieu."))*.