Perhaps you should try some spelling variations:
sach tranh » canh tranh
cong thanh » dong thanh, cong trinh, cong tan
canh ngon » danh ngon
ngon hoc » ngon doc, ngu hoc, mon hoc
cong khi » cong thai, khong khi, co khi
do canh » doi canh, do sanh, do danh
co sach » bo sach, cuon sach, hoc sach
hoc ki » hoc ky, hoc kinh, hoc khoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( do canh ngon hoc ki đong luc ) or ( co sach tranh ((cong khi) or (cong thanh)) đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( do canh ngon hoc ki đong luc ) OR ( co sach tranh ((cong khi) OR (cong thanh)) đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( do canh ngon hoc ki đong luc ) or ( co sach tranh ((cong khi) or (cong thanh)) đong luc ))*.