Perhaps you should try some spelling variations:
chiet tach » chieu sach
trung phan » trung thanh, trung ha, trung tuan
xuong cong » luong cong, duong cong, cuong cong
dung phan » dung nhan, dung luan, dung ha
cong toan » cong tan, cong hoan, cong tuan
so chiet » so thiet, soc thiet, so viet
toan bai » toan ban, toan tai, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: so chiet tach - thanh ((trung phan) or (dung phan)) xuong cong toan bai tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so chiet tach - thanh ((trung phan) OR (dung phan)) xuong cong toan bai tap.
• Adding a wildcard symbol may retrieve word variants: so chiet tach - thanh ((trung phan) or (dung phan)) xuong cong toan bai tap*.