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: Pantech Link P7040 AT&T Unlocked GSM QWERTY Cell Phone - Black
Product description: Pantech's P7040p is an exciting, ultraslim messaging phone with a large QVGA screen and soft textured finish on the back. It's designed for those seeking a feature packed, 3G messaging device at a value price that doesn't require a contract. With a host of GPS applications and messaging features like AT&T Navigator and AT&T Social Net, you can keep up with your friends and update your status anytime, anywhere.
Product feature: No contract hassles, Full QWERTY keyboard for texting, Mobile email, IM, text and picture messaging, AT&T Social Net, Web browsing, AT&T Navigator and AT&T Mobile Music, 1.3MP camera with video, Unlocked cell phones are compatible with GSM carriers like AT&T and T-Mobile as well as with GSM SIM cards (e.g. H20, Straight Talk, and select prepaid carriers). Unlocked cell phones will not work with CDMA Carriers like Sprint, Verizon, Boost or Virgin.
Product brand: Pantech
Target attributes: Operating System
Answer: attribute: operating system
value: None
source: None