Perhaps you should try some spelling variations:
sach tranh » canh tranh
tranh cong » thanh cong, trinh cong, tran cong
sanh nhanh » danh nhan, anh nhan, danh thanh
chong khi » khong khi, chong hiv, chong li
chong lai » chong li, chong mai, cong lai
cong khi » cong thai, khong khi, co khi
tu sach » thu sach, su sach, te sach
so sanh » do sanh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu sach tranh cong khi đong luc ) or ( so sanh nhanh ((chong khi) or (chong lai)) đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach tranh cong khi đong luc ) OR ( so sanh nhanh ((chong khi) OR (chong lai)) đong luc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach tranh cong khi đong luc ) or ( so sanh nhanh ((chong khi) or (chong lai)) đong luc ))*.