Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
tan hanh » tan thanh, tang hanh, toan hanh
van tieu » van hieu, van tien, vay tieu
te sach » toc sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty nang ((x hoi) OR (o hoi)). hieu ((va bai) or (vien cac)) duc tan hanh vi van tieu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty nang ((x hoi) OR (o hoi)). hieu ((va bai) OR (vien cac)) duc tan hanh vi van tieu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty nang ((x hoi) OR (o hoi)). hieu ((va bai) or (vien cac)) duc tan hanh vi van tieu".
• Adding a wildcard symbol may retrieve word variants: te sach ty nang ((x hoi) OR (o hoi)). hieu ((va bai) or (vien cac)) duc tan hanh vi van tieu*.