Perhaps you should try some spelling variations:
nam trung » nam trong, tai trung, ba trung
va trien » va truyen, va thiet, va tuyen
sach han » sach tham, sach danh, sach nang
trung va » truong va, trang va, trung ha
hanh vu » hanh vi, hanh va, hanh tu
va hanh » van hanh, va thanh, va danh
su sach » so sach, vu sach
hieu va » hieu qua
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
vu va » vu van, tu va, su va

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su sach han ((nang xa) OR (lang xa)) hoi. ((hieu va) OR (lieu va)) nam trung va hanh vu va trien~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach han ((nang xa) OR (lang xa)) hoi. ((hieu va) or (lieu va)) nam trung va hanh vu va trien~".
• Adding a wildcard symbol may retrieve word variants: su sach han ((nang xa) OR (lang xa)) hoi. ((hieu va) or (lieu va)) nam trung va hanh vu va trien*.