Perhaps you should try some spelling variations:
thuat do » thuat o
ki thuat » ky thuat
thuat co » thuat o
my thuat » ky thuat, va thuat
tu sach » thu sach, su sach, te sach
y thuat » ky thuat, kxy thuat, va thuat
sach ki » sach kinh, sach bai, sach kem
sach my » sach ty, sach mau, sach moi
do khi » doi khi, do thi, bo khi

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 y thuat do khi ) or ((( tu sach ki thuat co khi ) or ( tu sach my thuat co khi ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach y thuat do khi ) OR ((( tu sach ki thuat co khi ) OR ( tu sach my thuat co khi )))).
• Adding a wildcard symbol may retrieve word variants: (( tu sach y thuat do khi ) or ((( tu sach ki thuat co khi ) or ( tu sach my thuat co khi ))))*.