Very simple NEL system to be used as baseline taken from Hachey et al.
Given a mention, recognized by Stanford NER, it looks for the exact title on Wikipedia. If it finds any article, it assigns it as the linked entity. If not, it assigns NIL.
Ben Hachey, Will Radford, Joel Nothman, Matthew Honnibal, and James R. Curran. 2013. Evaluating Entity Linking with Wikipedia. Artif. Intell. 194 (January 2013), 130-150. Link