Perhaps you should try some spelling variations:
cua nuoc » cua quoc, cua nguoi, cua thuoc
van hanh » van thanh, ban hanh, van anh
dai hoi » dai hoc, dai moi
dai hai » dai han, dai tai, dai thao
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
luc van » luoc van, luu van, duc van
ty hang » ly hang, ty xang, thi hang
cua duc » cua tuc, cua quoc
su sach » so sach, vu sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty hang ((dai hoi) OR (dai hai)). hieu va cac luc van hanh vi ((cua duc) or (cua nuoc))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty hang ((dai hoi) OR (dai hai)). hieu va cac luc van hanh vi ((cua duc) OR (cua nuoc)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty hang ((dai hoi) OR (dai hai)). hieu va cac luc van hanh vi ((cua duc) or (cua nuoc))".
• Adding a wildcard symbol may retrieve word variants: su sach ty hang ((dai hoi) OR (dai hai)). hieu va cac luc van hanh vi ((cua duc) or (cua nuoc))*.