Instruction: Using the product's title, description, features, price, and brand, identify and retrieve the values associated with a specified set of target attributes. Output the extracted values along with their respective sources (e.g., title or feature) indicating where each value was found.

Input:
Product title: AMD Sempron 3300+ Socket A 2200MHz 512K L2 Cache CPU
Product description: 2200MHZ / 62W
Product feature: AMD Sempron 3300+ Socket A / Socket 462 CPU NO HEATSINK, Barton Core, 512K L2 Cache, SDA3300DKV4E, MMX, 3DNow!, SSE
Product brand: AMD
Target attributes: Number of Cores
Answer: attribute: number of cores
value: None
source: None