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: Lenovo Y50 Laptop Computer - 59421845 - Black - 4th Generation Intel Core i7-4710HQ / 8GB RAM / 15.6" FHD 1920x1080 Display / NVidia GeForce 860M 2GB / 1TB HDD + 8GB SSD / Dual Band Wireless AC / Windows 8.1
Product description: Powerful 15.6" multimedia and gaming laptop with cutting-edge graphics and processing, Full HD display, and premium audio.
Product feature: i7-4710HQ Processor (4C, 2.5GHz / turbo to 3.5GHz, 6MB, 1600MHz), NVIDIA GeForce GTX 860M, 2GB Memory, 15.6" FHD (1920x1080), 1TB 5400rpm+8GB SSHD, 8 GB RAM + Windows 8.1
Product price: $143.31
Product brand: Lenovo
Target attributes: Screen Size
Answer: attribute: screen size
value: 15.6"
source: product feature
attribute: screen size
value: 15.6"
source: product title
attribute: screen size
value: 15.6"
source: product description