Spartan helots

[Imperial Dave]

https://greekreporter.com/2024/06/29/sparta-treat-slaves/

More a social treatise and very limited butm may be of interest

[Erpingham]

If you like helots, Brett Deveraux covers them in his Sparta series here.  He goes into rather more on the complexity of estimating Helot numbers and their social roles.

[Imperial Dave]

absolutely more detail. the overview version is a handy reference but nothing more