Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
hieu cua » hieu qua, dieu cua, bieu cua
cua nhan » ca nhan, cua ngan, cua nha
nhan tuc » nhan thuc, nhan luc, nhanh thuc
te sach » toc sach
van han » van hanh, van phan, van nhan
tai cua » thai cua, tai cuc, tri cua
va han » va phan, va hanh, va hang
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach thu nang ((xa hoi) or (x ho)). hieu cua nhan tuc ((va han) OR (van han)) tai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach thu nang ((xa hoi) OR (x ho)). hieu cua nhan tuc ((va han) OR (van han)) tai cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach thu nang ((xa hoi) or (x ho)). hieu cua nhan tuc ((va han) OR (van han)) tai cua tu".
• Adding a wildcard symbol may retrieve word variants: te sach thu nang ((xa hoi) or (x ho)). hieu cua nhan tuc ((va han) OR (van han)) tai cua tu*.