Katy read twice as many books in July as she did in June, so she read 2 * 8 = <<2*8=16>>16 books in July.
She read three fewer books in August than she did in July, so she read 16 - 3 = <<16-3=13>>13 books in August.
So, including June, she read 8 + 16 + 13 = <<8+16+13=37>>37 books total
#### 37