Perhaps you should try some spelling variations:
chien duoc » chien luoc, chien cuoc, che duoc
van chien » van hien, van hieu, van tien
hieu van » hieu va, thien van, lieu va
duoc may » duoc ma, duoc ly, hoc may
tu sach » thu sach, su sach, te sach
via cua » gia cua, gian cua, giau cua
y nang » ky nang, ly nang, v nang
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: tu sach y nang ((x hoi) OR (o hoi)). hieu van chien duoc may tinh ((via cua) or (gian xu)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (o hoi)). hieu van chien duoc may tinh ((via cua) OR (gian xu)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((x hoi) OR (o hoi)). hieu van chien duoc may tinh ((via cua) or (gian xu)) te".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) OR (o hoi)). hieu van chien duoc may tinh ((via cua) or (gian xu)) te*.