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: Royal Classics FL60 Flamenco Nylon guitar Strings, Medium-High Tension
Product description: Royal Classics premium nylon guitar strings are made in Valencia, Spain under the direction of renowned guitarist and educator Juan Grecos. Designed as an essential component of great guitar tone, Royal Classics are manufactured to the highest standard from the most modern, technologically advanced machinery. A marriage of tradition and innovation, Royal Classics are relied upon for superb tone, consistency and stay-fast tuning by top professionals around the world.
Product feature: Royal Classics Flamenco set features high tension silverplated basses and traditional black flamenco trebles., Innovation meets tradition in this bright, expressive flamenco string recipe., Treble gauges: .71mm/.028", .81mm/.032", 1.02mm/.040" Bass gauges: .78mm/.031", .86mm/.034", 1.09mm/.043", Treated with an ultra thin proprietary anti-oxidant coating., Crafted in Spain by and for serious guitarists.
Product price: $16.99
Product brand: Royal Classics
Target attributes: Winding
Answer: attribute: winding
value: None
source: None