Perhaps you should try some spelling variations:
thieu nghiem » thi nghiem, thu nghiem, thieu nhi
tranh khien » trang kien, thanh hien, tran hien
khien khien » thien nhien, thien chien, khien dien
khien hoc » nhiet hoc, dien hoc
hoc sach » hoc sinh, hoc cac, hoc anh
nghiem y » nghiep y, nghiem _, nghiem d
so canh » so sanh, bo canh, so danh
bo sach » co sach

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 tranh khien khien hoc ) or ( ((bo sach) or (hoc sach)) thieu nghiem y hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so canh tranh khien khien hoc ) OR ( ((bo sach) OR (hoc sach)) thieu nghiem y hoc )).
• Adding a wildcard symbol may retrieve word variants: (( so canh tranh khien khien hoc ) or ( ((bo sach) or (hoc sach)) thieu nghiem y hoc ))*.