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
tu sach » thu sach, su sach, te sach
y thuat » ky thuat, my thuat, kxy thuat
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 ( tu 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 ( tu sach tranh kki thuat toan khoa )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu ((sach danh) OR (sach dao)) y thuat do hoc ) or ( tu 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 ( tu sach tranh kki thuat toan khoa ))*.