Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: HP Z210 Workstation, Intel Xeon E3-1220 3.1GHz Quad Core CPU, 32GB memory, 2TB hard drive, NVIDIA GeForce GTX 660 SuperClocked, Windows 7 Professional Installed
Product description: The single-socket HP Z210 Workstation is a fast single processor entry level workstation. The Z210 is a powerful business PC capable of heavy graphics and 3D workloads. The Z210 Workstation features the Intel Xeon E3-1200 series architecture for fast, energy-efficient performance on a variety of applications.This HP Z210 Workstation is equipped with the Intel Xeon E3-1220 3.1GHz six core processor, 32GB memory, 1x 2TB SATA hard drive, DVD-RW, NVIDIA Quadro GTX 660 SuperClocked and Windows 7 Professional installed.
Product feature: Xeon E3-1220 3.1GHz Quad Core Processor, 32GB DDR3 Memory, NVIDIA Quadro 2000, Windows 7 Professional 64-bit Installed
Product brand: HP
Target attributes: Number of Cores
Answer: attribute: number of cores
value: quad core
source: product feature
attribute: number of cores
value: quad core
source: product title