Can anyone suggest good reading material for mother of child with concentration problems

[ABitStretched]

Hi - ds1 (4) has been referred for ASD assessment which I know will take ages. I'm a bit 50:50 about the whole thing but have started implementing own things att home and seen huge improvement. Had a Special Needs assistant round today who can give me at home support for 6 weeks to work on specific issues. She said she wasn't convinced it was ASD, but there was definitely some developmental issues and its not attention seeeking (so stick that in your pipe and smoke it HV!!). She is arranging for EP to visit him at school and at home in addition to the paed assessment arranged by HV. Really happy with this. Will stop rambling now and get to the point....
One of the areas we have agreed to work on is building his attention span - it is shocking,can't listen to me for one sentence, will only do something if reminded every minute what it is he is doing, will give up on tasks really quickly. This is having knock onto his development, can't write his own name - won't even attempt more than one letter, can't dress / undress alone, doens't colour in etc etc. I think he is physically capable of all these things. SN lady recommended a techinique she described as sitting within a specific area,copying physical movements, getting them to concentrate on a task and then they get to do an activity of their choosing as a reward. Unfortunately we ran out of time and she can't come back for another 2 weeks to start work on it. Anyone know anything I can read book / online to find out more and start at home?? Or any advice - sorry to be so long-winded, just trying to give as much background as possible as it might help.

Cheers, ta