Perhaps you should try some spelling variations:
trinh thiet » trinh viet, trinh thi
sach trinh » sach tranh, hanh trinh, sach kinh
hanh tinh » hanh trinh, nhanh tinh, thanh tinh
dien hoc » dien hoa, khien hoc, tin hoc
te hanh » te thanh, tu hanh, ve hanh
su sach » so sach, vu sach
tu hoc » te hoc
du hoc » duoc 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 hanh tinh dien tu hoc ) OR ( su sach trinh thiet ((dien hoc) OR (du hoc)) ))~.
• Adding a wildcard symbol may retrieve word variants: (( te hanh tinh dien tu hoc ) or ( su sach trinh thiet ((dien hoc) or (du hoc)) ))*.