Perhaps you should try some spelling variations:
cau tren » cu tren, ca tren, cau treo
dau tren » dau tien, dat tren, dau tieng
tu sach » thu sach, su sach, te sach
ty nang » ty xang, ty hang, ly nang
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
va doan » va doanh, van doan, va dan
doan vi » doan va, don vi, doan thi
luc va » duc va, tuc va, loc va

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