Download the NT2GC72C89B0NJ datasheet PDF.
This datasheet also covers the NT2GC72B89B0NJ variant, as both devices belong to the same registered ddr3 sdram dimm family and are provided as variant models within a single manufacturer datasheet.
Note: The manufacturer provides a single datasheet file (NT2GC72B89B0NJ-NanyaTechnology.pdf) that lists specifications for multiple related part numbers.