Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: ASUS B43S-XH51 (14.1-Inch Screen) Laptop
Product description: 14.1" (1366x768) LED / Intel Core i5-2520M (2.4GHz) / 4GB DDR3 RAM / 500GB 7200 / DL DVDRW/CDRW / Windows 7 Professional (64bit) / 802.11BGN / 0.3MP Camera / Bluetooth 3.0 / USB 3.0 / 3 Cell Boston Power Battery / HDMI Port / Intel Vpro / Trusted Platform Module / Finger Print Reader / Support Trace / 3YR Global Warranty / 1YR Accidental Damage Protection / 30-Day Zero Bright Dot / 2-Way Free Shipping / 24-7 Tech Support
Product feature: 2.5 GHz Intel Core i5-2520M, 4 GB DIMM, 500 GB 7200 rpm Hard Drive, 14.1-Inch Screen, Windows 7 Professional
Product brand: Asus
Target attributes: Screen Size
Answer: attribute: screen size
value: 14.1-inch
source: product feature
attribute: screen size
value: 14.1-inch
source: product title
attribute: screen size
value: 14.1"
source: product description