Perhaps you should try some spelling variations:
hoach nganh » hoc nganh
sach tranh » canh tranh
tranh cong » thanh cong, trinh cong, tran cong
khoa khoa » hoa khoa, khuan khoa, hoc khoa
cong khi » cong thai, khong khi, co khi
khoa hoc » hoa hoc
tu sach » thu sach, su sach, te sach

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 sach tranh cong khi đong luc ) OR ( thu hoach nganh ((khoa khoa) OR (khoa hoc)) đong luc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach tranh cong khi đong luc ) or ( thu hoach nganh ((khoa khoa) OR (khoa hoc)) đong luc ))~".
• Adding a wildcard symbol may retrieve word variants: (( tu sach tranh cong khi đong luc ) or ( thu hoach nganh ((khoa khoa) OR (khoa hoc)) đong luc ))*.