Perhaps you should try some spelling variations:
canh trinh » canh tranh, hanh trinh, canh tinh
sach ngan » sach nha, sach han, sach nang
sach ngon » danh ngon, canh ngon, gach ngoi
trinh kxy » trinh ky, trinh ly, trinh ke
kxy thuat » ki thuat, my thuat, ky thua
thu canh » thuc hanh, thu cong, thu ban
toan hoc » toan khoa, van hoc, hoa hoc
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: (( tu ((sach ngan) OR (sach ngon)) ky thuat o hoc ) or ( thu canh trinh kxy thuat toan hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((sach ngan) OR (sach ngon)) ky thuat o hoc ) OR ( thu canh trinh kxy thuat toan hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu ((sach ngan) OR (sach ngon)) ky thuat o hoc ) or ( thu canh trinh kxy thuat toan hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu ((sach ngan) OR (sach ngon)) ky thuat o hoc ) or ( thu canh trinh kxy thuat toan hoc ))*.