Perhaps you should try some spelling variations:
cua quoc » cua nuoc, cua thuoc
van hanh » van thanh, ban hanh, van anh
thu sach » tu sach, thuat sach, thuoc sach
nang mai » nang ma, nang tai, lang mai
luc van » luoc van, luu van, duc van
cao luc » bao luc, cao duc, cao suc
su sach » so sach, vu sach
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » hieu qua
v nang » va nang, vu nang, van nang
vi cua » vai cua, di cua

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) or (thu sach)) v nang mai hoi. ((hieu va) OR (lieu va)) cao luc van hanh vi cua quoc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (thu sach)) v nang mai hoi. ((hieu va) OR (lieu va)) cao luc van hanh vi cua quoc.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (thu sach)) v nang mai hoi. ((hieu va) OR (lieu va)) cao luc van hanh vi cua quoc".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (thu sach)) v nang mai hoi. ((hieu va) OR (lieu va)) cao luc van hanh vi cua quoc*.