Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
nghien duoc » nghiem duoc, nghe duoc, nghia duoc
sach trinh » sach tranh, hanh trinh, sach kinh
thu nghiem » thuc nghiem, thi nghiem
nghiem de » nghiem d, nghiem do, nghiem te
toc sach » hoc sach, doc sach, thuoc sach
duoc hoc » quoc hoi
cac thu » cach thuc, cac thoi
ve cac » va cac, vien cac
de hoc » te hoc, du hoc, dien hoc

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: (( ve cac thu nghiem de hoc ) OR ( toc sach trinh nghien duoc hoc ))~.
• Adding a wildcard symbol may retrieve word variants: (( ve cac thu nghiem de hoc ) or ( toc sach trinh nghien duoc hoc ))*.