These entries are queried from radb.net using whois, you can try my project getting these.
:AS53414 route: 74.121.244.0/22 descr: custo route origin: AS53414 mnt-by: SI5-MNT changed: lindon.arthur [at] level3.com 20130313 source: LEVEL3 rpki-ov-state: valid route: 192.155.69.0/24 descr: Route for CloudOps, Inc. origin: AS53414 mnt-by: LEVEL3-MNT changed: joshua.hayes [at] level3.com 20171219 source: LEVEL3 rpki-ov-state: valid