Books for toilet training special needs children

[Tigerlion]

Has anyone read either:

"Toilet Training for Individuals with Autism..." (published by Jessica Kingsley)

or

"The Potty Journey - Guide to Toilet Training Children with Special Needs" (Autism Society).

I am struggling with potty training my 4 yr old DS (ASD) and would maybe purchase one of the books if anyone found them useful

Good tip re library but would still be interested to hear if anyone has read the Potty Journey?