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
toc sach » hoc sach, doc sach, thuoc sach
nganh ky » nganh y, nganh xay, hanh ky
thuat o » thuat do
o hoc » co hoc, mo hoc, so hoc

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