Perhaps you should try some spelling variations:
sach tranh » canh tranh
sach danh » sach dung, sach kinh
tranh kki » tranh cai
kki thuat » ki thuat, khoi thuat, ky thuat
sach dao » lanh dao
thuat do » thuat o
y thuat » ky thuat, my thuat, kxy thuat
te sach » toc sach
do hoc » co hoc, do hoa, du hoc
toan » tran

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 danh) or (sach dao)) y thuat do hoc ) or ( te sach tranh kki thuat toan khoa ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((sach danh) OR (sach dao)) y thuat do hoc ) OR ( te sach tranh kki thuat toan khoa )).
• Adding a wildcard symbol may retrieve word variants: (( tu ((sach danh) or (sach dao)) y thuat do hoc ) or ( te sach tranh kki thuat toan khoa ))*.