Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
nang doc » nang luc
hanh ve » hanh va, hanh kem
cac luc » cau luc, coc luc, cac nuoc
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
nang co » nang cao, nang noi, nang hoc
ca tren » cau tren, cu tren, la tren
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 ky ((nang co) OR (nang doc)) hoi. hieu vien cac luc va ((hanh ve) or (hanh vi)) ca tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang co) OR (nang doc)) hoi. hieu vien cac luc va ((hanh ve) OR (hanh vi)) ca tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang co) OR (nang doc)) hoi. hieu vien cac luc va ((hanh ve) or (hanh vi)) ca tren*".