I will give a small list of documentation on JunOS.
Day One: Beginner’s Guide to Learning Junos
https://files.ixnfo.com/Manuals/Juniper/junos-beginners-guide.pdf
https://www.juniper.net/documentation/en_US/day-one-books/junos-beginners-guide.pdf
Broadband Subscriber VLANs and Interfaces User Guide
https://files.ixnfo.com/Manuals/Juniper/subscriber-mgmt-vlan.pdf (2022-03-08)
https://www.juniper.net/documentation/us/en/software/junos/subscriber-mgmt-vlan/subscriber-mgmt-vlan.pdf
CLI Command Reference Guide
https://files.ixnfo.com/Manuals/Juniper/jatp-cli-reference.pdf
https://www.juniper.net/documentation/us/en/software/jatp/jatp-cli-reference/jatp-cli-reference.pdf
DHCP User Guide
https://files.ixnfo.com/Manuals/Juniper/dhcp.pdf (2022-03-09)
https://www.juniper.net/documentation/us/en/software/junos/dhcp/dhcp.pdf
BGP Best Current Practices
https://files.ixnfo.com/Manuals/Juniper/Best-Practick-BGP-BCP-Juniper.pdf
Настройка маршрутизаторов Juniper серии MX
https://files.ixnfo.com/Manuals/Juniper/pdf-juniper-mx_compress.pdf
Packet-Triggered абоненты @MX BNG
https://files.ixnfo.com/Manuals/Juniper/Packet-Triggered-abonenti-MX-BNG-v01-2.pdf
MX204 Datasheet
https://files.ixnfo.com/Manuals/Juniper/mx204-datasheet.pdf
MX204 3D Universal Edge Router Quick Start
https://files.ixnfo.com/Manuals/Juniper/mx204-quick-start.pdf
MX204 Universal Routing Platform Hardware Guide
https://files.ixnfo.com/Manuals/Juniper/mx204.pdf (2022-01-17)
https://www.juniper.net/documentation/us/en/hardware/mx204/mx204.pdf
See also my article:
Juniper MX204 setup