How could I find the version of openNURBS 4.0

I want to download a version of opennurbs 4 to be compared, but the link provided is opennurbs 5. What can I do? Thanks!

I am confused why you need an older version of openNURBS, as the current version reads both v5 and v4 files, and older too. What are you trying to do and why?

I worked on old version before. I just want to make comparison between my duplicate and the original. But I can’t find the original now.