Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
nghiem duoc » nghiem thuoc, nghe duoc
canh trinh » canh tranh, hanh trinh, canh tinh
sach trac » sach truc, sach tranh, sach tham
nghien te » nghiem te, nghiep ke, nghiep tu
che duoc » che thuoc, che do, te duoc
thu canh » thuc hanh, thu cong, thu ban
te sach » toc sach

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 trac ((nghiem duoc) OR (che duoc)) hoc ) OR ( thu canh trinh nghien te hoc ))~.
• Adding a wildcard symbol may retrieve word variants: (( te sach trac ((nghiem duoc) or (che duoc)) hoc ) or ( thu canh trinh nghien te hoc ))*.