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: Vans Mens Desert Chukka Boots
Product feature: Leather, Inspired by the original Chukka Boot silhouette., Uppers of durable suede., Ultracush footbed for all-day wear., Water-based inks and glues., Leather, Package Dimensions: 14.1 x 8.7 x 5.1 inches, Shipping Weight: 2.3 pounds, ASIN: B01DWZJHX0, Date first listed on Amazon: October 6, 2016, Average Customer Review: 4.5 out of 5 stars 2 customer reviews
Product brand: Vans
Target attributes: Style
Answer: attribute: style
value: vans
source: product title
attribute: style
value: vans
source: product brand