These entries are queried from radb.net using whois, you can try my project getting these.
:AS135998 route: 103.146.20.0/23 descr: IDBVIETNAM-VN origin: AS135998 mnt-by: MAINT-VN-VNNIC last-modified: 2024-04-08T07:57:46Z source: APNIC rpki-ov-state: valid route: 103.146.20.0/23 origin: AS135998 descr: VNPT-NET mnt-by: MAINT-AS45899 changed: radb [at] vnpt.vn 20231125 # 0150Z source: RADB last-modified: 2023-11-25T01:50:42Z rpki-ov-state: valid route: 103.146.20.0/24 descr: IDBVIETNAM-VN origin: AS135998 mnt-by: MAINT-VN-VNNIC last-modified: 2024-04-08T07:57:46Z source: APNIC rpki-ov-state: valid route: 103.146.20.0/24 descr: Vietnam Post and Telecom Corporation (VNPT) origin: AS135998 remarks: mailto: ktm.ip [at] vnpt.vn notify: vuxuannhan [at] vnpt.vn mnt-by: MAINT-AS45899 changed: radb [at] vnpt.vn 20200820 source: RADB last-modified: 2023-11-13T16:07:32Z rpki-ov-state: valid route: 103.146.21.0/24 descr: IDBVIETNAM-VN origin: AS135998 mnt-by: MAINT-VN-VNNIC last-modified: 2024-04-08T07:57:47Z source: APNIC rpki-ov-state: valid route: 103.146.21.0/24 descr: Vietnam Post and Telecom Corporation (VNPT) origin: AS135998 remarks: mailto: ktm.ip [at] vnpt.vn notify: vuxuannhan [at] vnpt.vn mnt-by: MAINT-AS45899 changed: radb [at] vnpt.vn 20200820 source: RADB last-modified: 2023-11-13T16:07:32Z rpki-ov-state: valid