The first 9 albums of the live 23 series contained a so called "voucher". Album no. 10 ("psychedelic violence") was only available for sending in all 9 vouchers.

voucher 1 from "live in tokyo"

voucher 2 from "live in paris"

voucher 3 from "live in heaven"

voucher 4 from "live in glasgow"

voucher 5 from "live in reykjavik"

voucher 6 from "live in suisse"

voucher 7 from "live in goettingen"

voucher 8 from "live in toronto"

voucher 9 from "temporary temple"