Candidate members should also be familiar with CSA's body of knowledge on SPD:
https://cloudsecurityalliance.org/artifacts/sdp-architecture-guide-v2/
https://cloudsecurityalliance.org/artifacts/software-defined-perimeter-and-zero-trust/
https://cloudsecurityalliance.org/artifacts/software-defined-perimeter-as-a-ddos-prevention-mechanism/
https://cloudsecurityalliance.org/artifacts/software-defined-perimeter-glossary/
https://cloudsecurityalliance.org/artifacts/sdp-for-iaas/
https://cloudsecurityalliance.org/artifacts/sdp-specification-v1-0/
https://cloudsecurityalliance.org/artifacts/sdp-hackathon-whitepaper/
https://cloudsecurityalliance.org/artifacts/software-defined-perimeter/