Perhaps you should try some spelling variations:
cac nganh » hoc nganh
sach tinh » sach kinh, sac tinh, sach tranh
toc sach » hoc sach, doc sach, thuoc sach
cong khi » cong thai, khong khi, cong hai
tinh co » trinh co, tinh cao, tinh cho
cong ha » cong hoa, dong ha, cong tac
te cac » tu cac, ve cac, te cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( toc sach tinh co khi đong luc ) or ( te cac nganh ((cong khi) OR (cong ha)) đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( toc sach tinh co khi đong luc ) OR ( te cac nganh ((cong khi) OR (cong ha)) đong luc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( toc sach tinh co khi đong luc ) or ( te cac nganh ((cong khi) OR (cong ha)) đong luc ))".
• Adding a wildcard symbol may retrieve word variants: (( toc sach tinh co khi đong luc ) or ( te cac nganh ((cong khi) OR (cong ha)) đong luc ))*.