Perhaps you should try some spelling variations:
trinh khien » trinh thien, trinh nghien, trinh thiet
canh trinh » canh tranh, hanh trinh, canh tinh
khien tin » khien tinh, khien dien, thien tinh
so canh » so sanh, bo canh, so danh
tin hoc » sinh hoc
bo sach » co sach, hoc sach
nhi y » nghi y, nho y, nhu y
nhi o » nha o, chi o
thieu » hieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so canh trinh khien tin hoc ) or ( bo sach thieu ((nhi y) OR (nhi o)) hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so canh trinh khien tin hoc ) OR ( bo sach thieu ((nhi y) OR (nhi o)) hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( so canh trinh khien tin hoc ) or ( bo sach thieu ((nhi y) OR (nhi o)) hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( so canh trinh khien tin hoc ) or ( bo sach thieu ((nhi y) OR (nhi o)) hoc ))*.