Blues scale + 3rd?

[OliBeau]

I learned the blues scales long time ago but I received a book from my teacher on blues and it's saying something a little strange...

They wrote that blues scale is made with : the root, half tone diminished 3rd, *3rd, 4th, half tone diminished 5th, halftone lowered 7th.

What's strange is that I always learned that the blues scales don't have a 3rd (not diminished..)...

If it was a cheap book I would say that it's a mistake but it seems to be good (a Hanon book...).

Can someone help me on this ?

OliBeau