Schneidermusik list Dr Junger - as single srings. They also sell Jose Ramerez and they sell Knobloch !
For Dr Junger search 6 string classical guitar single strings - or just search Dr Junger !
It would seem though that Dr Junger are being discontinued as they are listed as remaining stocks only.
https://schneidermusik.de/shop1/advance ... /397_1_399