Perhaps you should try some spelling variations:
doanh vi » doanh va, doan vi, doanh vien
va doanh » van doanh, vay doanh, va danh
van hach » van hanh, van hac, van sach
van bach » van bac, van sach, vien bach
tuoc va » thuoc va, nuoc va, duoc va
te sach » toc sach
lua tre » cua tre, luy tre, dua tren
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
vi lua » vi luu
o hoi » co hoi, o hoc, o hai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach v nang ((5 hoi) OR (o hoi)). hieu ((van bach) OR (van hach)) tuoc va doanh vi lua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach v nang ((5 hoi) or (o hoi)). hieu ((van bach) OR (van hach)) tuoc va doanh vi lua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach v nang ((5 hoi) or (o hoi)). hieu ((van bach) OR (van hach)) tuoc va doanh vi lua tre*.