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: ViewSonic VT1901LED 19-Inch 720p 60Hz Professional Monitor with HDTV Functionality (Black)
Product description: ViewSonic's new VT1901LED is a professional monitor with HDTV functionality The VT1901LED features "Edge White" LED technology delivering brilliant image clarity, high contrast with saturated colors while consuming very low power. Versatile connectivity is provided through HDMI in addition to PC and traditional YPbPr component video and USB. Internal programming is offered for users wanting to set up specific product calibration. Extreme audio includes internal equalizer with SPDIF digital output.
Product feature: 18.5-Inch "Edge White" HD LED panel, 1366x768 resolution, Programmable TV set-up operation and USB cloning, USB Multimedia player, ATSC, HDMI, VGA, CVBS, USB and component video input, 2.5W audio, Equalizer audio selections, 100mm x 100mm VESA mounting, 1-Year limited warranty, Stand included, Wall mount WM-U1
Product brand: ViewSonic
Target attributes: Viewing Angle
Answer: attribute: viewing angle
value: None
source: None