Perhaps you should try some spelling variations:
doi chieu » doc hieu, doi chi, mot chieu
cong thuc » cong tac
thuc mang » thuc trang, thuoc dang, thuat mang
mang cong » dang cong, bang cong, hang cong
cong lang » cong vang, cong luong, cong quang
lang phan » nang phan, lang thang, lang phong
phan cac » nhan cach, phan dau, phan lap

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doi chieu) OR (toc thieu)) sach - thanh cong thuc mang cong lang phan cac~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doi chieu) OR (toc thieu)) sach - thanh cong thuc mang cong lang phan cac".
• Adding a wildcard symbol may retrieve word variants: ((doi chieu) OR (toc thieu)) sach - thanh cong thuc mang cong lang phan cac*.