Perhaps you should try some spelling variations:
sach tranh » canh tranh
sach ngan » sach ngon, sach nha, sach han
toan hoc » toan khoa, van hoc, hoa hoc
tranh va » tranh van, trang va, trinh va
va thuat » ki thuat, va thuc, va thiet
tu sach » thu sach, su sach, te sach
ngan ky » nganh ky, nhan ky, ngan hay
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 ky thuat toan hoc ) or ( tu sach tranh va thuat o hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ngan ky thuat toan hoc ) OR ( tu sach tranh va thuat o hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach ngan ky thuat toan hoc ) or ( tu sach tranh va thuat o hoc ))*.