Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
nay xua » nam xua, nay lua, ngan xua
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
va xanh » va danh, va anh, va banh
di dau » doi dau, bi dau, di du
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
ro hoi » co hoi, mo hoi, ro doi
va nay » va ngay, va cay
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 sac ky nang ((ro hoi) or (o hoi)). hieu va nay xua ((va xanh) OR (va hanh)) di dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky nang ((ro hoi) OR (o hoi)). hieu va nay xua ((va xanh) OR (va hanh)) di dau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky nang ((ro hoi) or (o hoi)). hieu va nay xua ((va xanh) OR (va hanh)) di dau tren*".