Perhaps you should try some spelling variations:
sach nganh » sach ngan, cac nganh, sach danh
nganh cong » nhanh chong, thanh cong
sach thanh » sach tham, danh thanh, sach danh
sach tranh » canh tranh
cong khi » cong thai, khong khi, co khi
so sach » so sanh, bo sach, co sach
hoa thi » hoa thai, ha thi, hoa phi

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

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