Perhaps you should try some spelling variations:
tranh nghiem » trac nghiem, trach nhiem, trinh nghien
sach tranh » canh tranh
can tranh » canh tranh, tan tran, van ranh
nghiem d » nghiem de, nghiem _, nghiem h
so sach » so sanh, bo sach, co sach
tu can » tu ban, tu cac, thu canh
de hoc » te hoc, dien hoc
du hoc » duoc hoc
tu hoc » te hoc
d hoc » ad hoc, y hoc, _ 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: (( tu can tranh nghiem ((((de hoc) OR (du hoc))) OR (tu hoc)) ) OR ( so sach tranh nghiem d hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu can tranh nghiem ((((de hoc) OR (du hoc))) or (tu hoc)) ) or ( so sach tranh nghiem d hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( tu can tranh nghiem ((((de hoc) OR (du hoc))) or (tu hoc)) ) or ( so sach tranh nghiem d hoc ))*.