Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
toc sach » hoc sach, doc sach, thuoc sach
tu sach » thu sach, su sach, tu cach
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 cau » va cau, ve cau, di cau

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) OR (toc sach)))) ky nang x ho. hieu qua cau luc va doan vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (((te sach) OR (toc sach)))) ky nang x ho. hieu qua cau luc va doan vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (((te sach) OR (toc sach)))) ky nang x ho. hieu qua cau luc va doan vi cau tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (((te sach) OR (toc sach)))) ky nang x ho. hieu qua cau luc va doan vi cau tren*.