Perhaps you should try some spelling variations:
khau viet » khoan viet, phap viet, hai viet
hieu van » hieu va, thien van, lieu va
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
tai khau » tai khu, tai khoan, tai khoa
su sach » so sach, vu sach
ty nang » ky nang, ty xang, ty hang
hieu ve » hieu va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (su sach)) ty nang x ho. ((hieu ve) OR (hieu van)) chat va van hanh tai khau viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (su sach)) ty nang x ho. ((hieu ve) OR (hieu van)) chat va van hanh tai khau viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (su sach)) ty nang x ho. ((hieu ve) OR (hieu van)) chat va van hanh tai khau viet".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (su sach)) ty nang x ho. ((hieu ve) OR (hieu van)) chat va van hanh tai khau viet*.