Instruction: Extract the value of the target attribute from the given product information and output it along with the corresponding source.

Input:
Product title: Kozy World KWN323 30,000-BTU Vent-Free Natural-Gas Infrared Wall Heater with Thermostat
Product description: Brought to you by world marketing, this wall heater is made of heavy-duty steel with a neutral paint finish. The fuel efficient heater, features top mounted controls and matchless piezo ignition, making it extremely easy to operate. For added safety, it is equipped with an oxygen depletion sensor and flame failure system. Utilizing an innovative technology, the radiant plaques heat people and objects in the room prior to heating the air. Designed with convenience in mind, the heater can operate without electricity, making it ideal for use during power outages. Certified by csa, the heater provides safe, odorless, and clean burning.
Product feature: Size 23.5 inch h x 19.25 inch w x 8.0 inch d, Heavy-duty steel construction, Matchless ignition, Great for use during power outages
Product brand: Kozy World
Target attributes: Heat Source
Answer: attribute: heat source
value: fuel
source: product description
attribute: heat source
value: natural
source: product title