The Global Supply of Vacuum Tubes: What Happens Now? – PS Audio
Electro-Harmonix Russian Vacuum Tubes: A Solution Found? - gearnews.com
David Grenache, PhD on Twitter: "The shortage of sodium citrate blood collection tubes for coagulation tests continues. Now we have patients showing up with blue-top tubes they bought online. No manufacturer info
The Internal Life of Vacuum Tubes | audioXpress
Mike Matthews owner of Electro Harmonix says no more Russian vacuum tubes in 2022 - gearnews.com