Straight from the source ...
PCI Data Storage Do’s and Don’ts - https://www.pcisecuritystandards.org/pdfs/pci_fs_data_storage.pdf
Payment Card Industry Security Standards Overview - https://www.pcisecuritystandards.org/pdfs/pcissc_overview.pdf
Ten Common Myths of PCI DSS - https://www.pcisecuritystandards.org/pdfs/pciscc_ten_common_myths.pdf