These entries are queried from radb.net using whois, you can try my project getting these.
:AS393661 route: 192.252.8.0/21 descr: NEVADACOUNTY-CA-192.252.8.0-21 origin: AS393661 mnt-by: MAINT-AS393661 changed: network_managers [at] co.nevada.ca.us 20201203 source: ALTDB rpki-ov-state: not_found # No ROAs found, or RPKI validation not enabled for source route: 192.252.8.0/23 descr: NEVADACOUNTY-CA-192.252.8.0-21 origin: AS393661 mnt-by: MAINT-AS393661 changed: network_managers [at] co.nevada.ca.us 20201203 source: ALTDB rpki-ov-state: not_found # No ROAs found, or RPKI validation not enabled for source route: 192.252.8.0/23 descr: Nevada IGS origin: AS393661 mnt-by: MAINT-AS54048 changed: msouders [at] cvin.com 20170519 #16:11:16Z source: RADB last-modified: 2023-11-13T15:51:12Z rpki-ov-state: not_found # No ROAs found, or RPKI validation not enabled for source route: 192.252.10.0/23 descr: NEVADACOUNTY-CA-192.252.8.0-21 origin: AS393661 mnt-by: MAINT-AS393661 changed: network_managers [at] co.nevada.ca.us 20201203 source: ALTDB rpki-ov-state: not_found # No ROAs found, or RPKI validation not enabled for source