I am also interested in this topic. You might have already read it but Alf Ludtke on on East German border checkpoints in the Journal of Contemporary History is good

I'm specifically looking for something global & pophistory/undergraduate friendly - it's not an area of expertise for me (quarantine aside); any suggestions?I'm specifically looking for something global & pophistory/undergraduate friendly - it's not an area of expertise for me (quarantine aside); any suggestions?