Perhaps you should try some spelling variations:
sach ngan » sach ngon, sach nha, sach han
trinh kxy » trinh ly, trinh ke, trinh may
toan hoc » toan khoa, van hoc, hoa hoc
tu sach » thu sach, su sach, te sach
ngan ky » nganh ky, nhan ky, ngan hay
thuat o » thuat do
tu hanh » du hanh, lu hanh, thuc hanh
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: (( tu sach ngan ky thuat o hoc ) or ( tu hanh ((trinh kxy) OR (trinh ky)) thuat toan hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ngan ky thuat o hoc ) OR ( tu hanh ((trinh kxy) OR (trinh ky)) thuat toan hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu sach ngan ky thuat o hoc ) or ( tu hanh ((trinh kxy) OR (trinh ky)) thuat toan hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu sach ngan ky thuat o hoc ) or ( tu hanh ((trinh kxy) OR (trinh ky)) thuat toan hoc ))*.