Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
tu sach » thu sach, su sach, tu cach
te sach » toc sach
qua cau » quan cau, qua cac, qua ca
cau luc » cau truc, cau phuc
va doan » va doanh, van doan, va dan
doan vi » doan va, don vi, doan thi
luc va » duc va, tuc va, loc va
vi dau » vi dai, va dau, bi dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (te sach)) ky nang x ho. hieu qua cau luc va doan vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang x ho. hieu qua cau luc va doan vi dau tren.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang x ho. hieu qua cau luc va doan vi dau tren*.