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: Lakewood Oil Filled Radiator Heater (5600/7)
Product description: Sold as one unit. (1 unit = each.) Three heat settings: 600/ 900/1500 watts. Internal tip-over switch. Safety thermal cut-off. Thermostat temperature control - automatic on/off cycles. Casters for portability. Convenient handle. Permanently sealed oil reservoir - never needs refilling. Cord storage. Boxed. Manufacturer number: 5600/7. SKU #: 69590. Country of origin: China. Distributed by Ace Trading - Lakewood 5.
Product brand: ACE
Target attributes: Heat Source
Answer: attribute: heat source
value: oil
source: product title
attribute: heat source
value: oil
source: product description