Perhaps you should try some spelling variations:
ban thanh » ban hanh
tay quang » tac quang, tai quang, tao quang
ban hang » ngan hang
sach tay » xach tay, sach hay, sach nay
nhan luc » nang luc
su sach » so sach, vu sach
tai cua » thai cua, tai cuc, tri cua
va nhan » van nhan, ca nhan, va phan
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va hoa » va hoc, ma hoa

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 tay quang ((va hoa) OR (van hoa)). hieu va nhan luc ((ban thanh) or (ban hang)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tay quang ((va hoa) OR (van hoa)). hieu va nhan luc ((ban thanh) OR (ban hang)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach tay quang ((va hoa) OR (van hoa)). hieu va nhan luc ((ban thanh) or (ban hang)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach tay quang ((va hoa) OR (van hoa)). hieu va nhan luc ((ban thanh) or (ban hang)) tai cua tre*.