How to harvest metadata of individual issue with OAI

Hello everyone.

First of all let me thank you for providing such wonderful application. The way you people are continuously updating it also demands appreciation.

I want to only harvest metadata of individual issues published in OJS. I traced out following available options :

REST API: Supports OJS 3.x. It also needs authentication.
OAI: Supports OJS 2/3. No authentication is required.

Using the below link, I can collect metadata of individual articles:

My requirement is to harvest metadata of individual issues. For example, issue no 3. How can I do that? Moreover, as I can see the usage guide of REST API at REST API Usage Guide. Is there any documentation available for OAI?

Thank you for your time.