How to produce this variant of letter 'a'? [duplicate]

I would like to produce a variant of letter a as shown below

The source is Shoenfield's Mathematical Logic book (first occurrence in p18) and it is used to denote structures. It appears (to me) like a large calligraphic variant of lowercase a. I use \cal A instead, and I have also looked over some other alternatives (e.g. the \frac ones) but I would like to use that precise symbol in my notes if possible.

The results from detexify were not really that useful in this case either:

• Welcome to TeX.SE! Nov 13 '21 at 16:26
• Nov 13 '21 at 17:08

This symbol is available from the "curly" variant of the commercial MTPro2 package. See the MTPro2 package homepage for more information.
[Disclaimer: I am in no way affiliated with MTPro2, but it is the only place I know that has the symbol]