How to correct yellowed primer colors?

I have this primer whose cover and pages got yellowed by time. I scanned the cover and a couple of pages I want to put in my portfolio. I could manage to make the pages almost entirely black and white while preserving some gray areas of the illustrations. For this I first used IrfanView to convert the images to black and white, then used PP to remove moiré and noise.

But the cover is a challenge I have no idea how to overcome. I want to make the cover background white, the blacks to be 100% black, the grays to have their shades preserved and, most important, to preserve the green to black gradient effect in the title.

Would you please help me with that? TIA!

No Data
Reply Children