Where/how can I now obtain/purchase the original Retin-A cream, which I used for 20 years + with very satisfying results?

How/where may I now obtain the original Retin-A cream (which I used very satisfactorily for 20 years plus....up until a few years ago, when told was no longer made or available worldwide?) i.e. original product I believe was in a base of 'retinoic acid' ?

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