Perhaps you should try some spelling variations:
sach trinh » sach tranh, hanh trinh, sach kinh
trinh nghe » trinh nghien, trinh he, trinh nha
tranh thai » trang thai, tran thi, tinh thai
khien hoc » nhiet hoc
dien hoc » dien hoa, tin hoc, lieu hoc
te sach » toc sach
nghe di » nghe vi, nghe dien, nghe dan
tu canh » thu canh, tu chanh, tu can
di hoc » dai hoc, dia hoc, li hoc

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( te sach trinh nghe di hoc ) or ( tu canh tranh thai ((dien hoc) OR (khien hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach trinh nghe di hoc ) OR ( tu canh tranh thai ((dien hoc) OR (khien hoc)) )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( te sach trinh nghe di hoc ) or ( tu canh tranh thai ((dien hoc) OR (khien hoc)) ))".
• Adding a wildcard symbol may retrieve word variants: (( te sach trinh nghe di hoc ) or ( tu canh tranh thai ((dien hoc) OR (khien hoc)) ))*.