In print or not, most anything and everything is still available, either through Amazon or Abebooks. A partial list took less than five minutes, with most prices generally less than US 20.00; some even under 10.00 . . .
Karnivoren by Barthlott, et al (now in English as well as The Curious World of Carnivorous Plants: A Comprehensive Guide to Their Biology and Cultivation); Carnivorous Plants by Tony Camilleri; The Savage Garden by Peter D'Amato; Cultivating Carnivorous Plants by Natch Greyes; Carnivorous Plants: Care and Cultivation by Marcel Lecoufle; Carnivorous Plants of the World by Janes Pietropaolo; Growing Carnivorous Plants in the Tropics by Cindy Chaing Lih Pyng; Growing Carnivorous Plants by Barry Rice; Carnivorous Plants by Randall Schwartz; Carnivorous Plants by Adrian Slack; Insect Eaters and Insect Eating Plants and How to Grow Them by Adrian Slack . . .
Nothing really substantial has changed in terms of cultivation practices; and my most valued books still date from the 1980s . . .