Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
tu sach » thu sach, su sach, te sach
ca tren » cau tren, la tren, co tren
hanh ve » hanh va, hanh kem
cac luc » cau luc, coc luc, cac nuoc
nang co » nang cao, nang doc, nang noi
cu tren » tu tren, dua tren
luc va » duc va, tuc va, loc va
y nang » ky nang, ly nang, v nang
co hoi » co hoc, co loi

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 y nang co hoi. hieu vien cac luc va ((hanh ve) or (hanh vi)) ((ca tren) OR (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang co hoi. hieu vien cac luc va ((hanh ve) OR (hanh vi)) ((ca tren) OR (cu tren))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang co hoi. hieu vien cac luc va ((hanh ve) or (hanh vi)) ((ca tren) OR (cu tren))*".