Instruction: First, identify the target attributes from the provided list. Then, scan the product title, description, feature, and brand to extract the values associated with each target attribute. Finally, create a list of dictionaries, each containing the extracted attribute, its corresponding value, and the source where it was found.

Input:
Product title: Dell Inspiron 3000s Intel G1820 Dual 2.7GHz, 4GB RAM, Windows 7, 500GB HDD Desktop Computer
Product description: Processor & Memory: Intel Celeron G1820 Processor 2.7GHz 4GB DDR3 1600MHz RAM Drives: 500GB 7200RPM SATA Hard Drive DVD-RW (Writes to DVD/CD) Operating System: Windows 7 Home Premium (64-bit) Graphics & Video: Intel HD Graphics Communications: Dell Wireless-N 1705 + Bluetooth 4.0 Keyboard & Mouse: Dell USB Keyboard & Optical Mouse I/O Ports & Slots: 2x USB 3.0 6x USB 2.0 1x Multi-Media Card Reader 1x Combination headphone / microphone jack 1x 3-stack Audio Jacks supporting 5.1 Surround Sound 1x VGA 1x RJ-45 Additional Information: Dimensions: 10.4\"H x 3.9\"W x 14.8\"D Approximate Weight: 13.22lbs
Product feature: Intel Dual-Core G1820 (2.7 GHz), 4GB Memory, 500GB Hard Drive, Windows 7 Home Premium, Intel HD Integrated Graphics
Product brand: Dell
Target attributes: Operating System
Answer: attribute: operating system
value: windows 7
source: product feature
attribute: operating system
value: windows 7
source: product title
attribute: operating system
value: windows 7
source: product description