Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
cong thai » cong hai, hong thai, cong thanh
nganh yng » nganh cong, nganh nong, nganh y
cong khi » khong khi, co khi, cong ha
vu sach » vu bach, vu khach
su sach » so sach
yng khi » bang khi, dong khi, dung khi

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: (( vu sach nganh ((cong khi) OR (cong thai)) đong luc ) OR ( su sach nganh yng khi đong luc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( vu sach nganh ((cong khi) OR (cong thai)) đong luc ) or ( su sach nganh yng khi đong luc ))~".
• Adding a wildcard symbol may retrieve word variants: (( vu sach nganh ((cong khi) OR (cong thai)) đong luc ) or ( su sach nganh yng khi đong luc ))*.