Black side of a Catalan.
i think pert's ragozin covers the catalan. that's the only book i know of the ragozin/nimzo out there. i have sielecki's nimzo ragozin but it's a video format. the catalan is covered there along with other d4 sidelines with a fianchetto. the 4..b5 idea came from avrukh's book though, and i forgot the title. you'll probably find it because he is famous.

o livro do colovic pro chessable tem uma recomendação legal contra a catalã, mais o repertório completo é de gambito recusado, ent n sei se serve pra vc
The best modern book is a data base. Printed books are obsolete while being printed. Look at recent grandmaster games, e.g. from the Yekaterinburg Candidates Tournament.

I was wondering if there are any good modern book references about playing vs the Catalan. As I play Nimzo/Ragozin set-ups it's not quite there the knowledge to play vs Catalã, as it's not a Nimzo or Ragozin anymore. I'm currently doing my own work in the databases, but it would be wonderful if there are books on the subject for giving me a good start. So, does anyone have recommendations? Thank you for your time.
I only play Catalan as white so I don’t know of any books. But what I do when making a repertoire is look up the lines (YouTube, Wikipedia, etc) and find a line at random that looks nice, play it over and over again, and just learn the common ideas, motifs, etc. you can also look at gm games to see The common themes, ideas, and plans.

I was wondering if there are any good modern book references about playing vs the Catalan. As I play Nimzo/Ragozin set-ups it's not quite there the knowledge to play vs Catalã, as it's not a Nimzo or Ragozin anymore. I'm currently doing my own work in the databases, but it would be wonderful if there are books on the subject for giving me a good start. So, does anyone have recommendations? Thank you for your time.
I only play Catalan as white so I don’t know of any books. But what I do when making a repertoire is look up the lines (YouTube, Wikipedia, etc) and find a line at random that looks nice, play it over and over again, and just learn the common ideas, motifs, etc. you can also look at gm games to see The common themes, ideas, and plans.
Same. I only play as White. As if my games didn't show.
I was wondering if there are any good modern book references about playing vs the Catalan. As I play Nimzo/Ragozin set-ups it's not quite there the knowledge to play vs Catalã, as it's not a Nimzo or Ragozin anymore. I'm currently doing my own work in the databases, but it would be wonderful if there are books on the subject for giving me a good start. So, does anyone have recommendations? Thank you for your time.