Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
nganh ky » nganh y, nganh xay, hanh ky
thuat do » thuat o
y thuyet » ly thuyet, li thuyet
ly huyet » ly thuyet, li thuyet, ly chuyen
su sach » so sach, vu sach
tu sach » thu sach, te sach, tu cach
do hoa » dong hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach nganh ky thuat do hoa ) or ( tu sach nganh ((y thuyet) OR (ly huyet)) hoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach nganh ky thuat do hoa ) OR ( tu sach nganh ((y thuyet) OR (ly huyet)) hoa hoc ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach nganh ky thuat do hoa ) or ( tu sach nganh ((y thuyet) OR (ly huyet)) hoa hoc ))*".