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