The ISO/IEC 15408 PDF document can be downloaded from the ISO website or other online sources. The document is available in several languages and can be purchased or downloaded for free.
– Focuses on the "trust" aspect, defining the rigor of the evaluation process. iso iec 15408 pdf
What specific you are trying to certify (e.g., operating system, cloud service, network hardware)? The ISO/IEC 15408 PDF document can be downloaded