Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
thuyet hoa » thuyet va, huyet hoc
ky thuyet » ly thuyet, li thuyet, ly huyet
nganh ky » nganh y, nganh xay, hanh ky
thuat do » thuat o
su sach » vu sach
so sach » so sanh, bo sach, co sach
do hoc » co hoc, do hoa, du hoc

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 hoc ) or ( so sach nganh ky thuyet hoa hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach nganh ky thuat do hoc ) OR ( so sach nganh ky thuyet hoa hoc )).
• Adding a wildcard symbol may retrieve word variants: (( su sach nganh ky thuat do hoc ) or ( so sach nganh ky thuyet hoa hoc ))*.