Perhaps you should try some spelling variations:
hanh dai » hanh tai, hanh dao, vanh dai
van hanh » van thanh, ban hanh, van anh
van nang » van quang, van ban, van dong
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
luc van » luoc van, luu van, duc van
cau luc » cau truc, cau phuc
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
tai hoa » tai khoa, thai hoa, thi hoa
v nang » va nang, vu nang, voi nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((v nang) or (van nang)) tai hoa. ((hieu ve) OR (hieu va)) cau luc van hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((v nang) OR (van nang)) tai hoa. ((hieu ve) OR (hieu va)) cau luc van hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((v nang) or (van nang)) tai hoa. ((hieu ve) OR (hieu va)) cau luc van hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ((v nang) or (van nang)) tai hoa. ((hieu ve) OR (hieu va)) cau luc van hanh dai cua tre*.