Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
thuoc sach » hoc sach, nuoc sach, thuat sach
thi nghiem » thuc nghiem
sach trinh » sach tranh, hanh trinh, sach kinh
nghiem d » nghiem de, nghiem _, nghiem h
nghien d » nghien o, nghiem de, nghiep di
te sach » toc sach
su sach » so sach, vu sach
d hoc » du hoc, ad hoc, de 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: (( ((te sach) OR (su sach)) thi nghiem d hoc ) OR ( thuoc sach trinh nghien d hoc ))~.
• Adding a wildcard symbol may retrieve word variants: (( ((te sach) or (su sach)) thi nghiem d hoc ) or ( thuoc sach trinh nghien d hoc ))*.