The specific chapter about this is here - [Sampling Theory][1]<br>
Unlike what I read anywhere else, it defines Shah as: $$Ш_T(x)=T\sum\nolimits_i{\delta{(x-Ti)}}$$
Elsewhere it's always simply: $$s_T{(x)}=\sum\nolimits_i{\delta{(x-Ti)}}$$
And the T is still present in the reconstructed function: $$f\tilde(x)=T\sum\limits_{i=-\infty}^\infty{f(iT)r(x-iT)}$$
where r(x) is a reconstruction filter.<br>
Can someone work out the maths for me to understand?

I haven't been doing maths for years, and even back in my school days, I don't think I was a good student, so please be gentle.

  [1]: http://www.pbr-book.org/3ed-2018/Sampling_and_Reconstruction/Sampling_Theory.html