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: Epiphone Limited Edition 1961 Casino Royal Electric Guitar in Tan
Product description: 50th Anniversary Issue of the Classic 1961 Epiphone Casino
Product feature: Classic Dogear P-90 Pickups for Vintage Tone and Bite, 5 Ply Maple Top, Back, and Sides, Limited Production, Special 50th Anniversary Model, Hardshell Case Included
Product brand: Epiphone
Target attributes: Number of Strings
Answer: attribute: number of strings
value: None
source: None