Perhaps you should try some spelling variations:
dau tien » van tien
dau tren » dat tren, dau tieng, dau trong
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cac luc » cau luc, coc luc, cac nuoc
cu tren » tu tren, dua tren
luc va » duc va, tuc va, loc va
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban 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 ky nang x ho. hieu va cac luc va dan va ((cu tren) or (((dau tren) OR (dau tien))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x ho. hieu va cac luc va dan va ((cu tren) OR (((dau tren) OR (dau tien)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x ho. hieu va cac luc va dan va ((cu tren) or (((dau tren) OR (dau tien))))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x ho. hieu va cac luc va dan va ((cu tren) or (((dau tren) OR (dau tien))))*.