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: Hohner Special Twenty Harmonica, Key of F
Product description: Special 20 (#560) Awesome response, superior bendability and the sweetest tone ever. This harp is the first choice for those learning to play. Its special airtight design makes it the most recommended go-to harp for harmonica players of any style, including blues, country, folk or rock. The plastic comb doesnt absorb moisture making it longer lasting. Harp of choice of harmonica virtuoso John Popper (of Blues Traveler) and played by Bob Dylan on his 2007/08 tour. Chances are your favorite player has several of these harps in his case. 12 major keys plus lower and higher octave tunings. Also available in a Special Country tuning with a major 7th in cross harp position.
Product feature: Played by the Pros, Smooth Plastic Body for fast Playing, Responsive Reeds, German Quality and Craftsmanship
Product price: $7.99
Product brand: Hohner Accordions
Target attributes: Key
Answer: attribute: key
value: key of f
source: product title