Negative Vote articles:

The concept of Negative Vote is sometimes referred to as:  CAV(Combined approval voting), Bipolar Voting, or Formal Recognition of the Negative Preferences
Following are various papers that specifically deal with the Negative Vote concept.  

1. Boehm, G.A.W. (1976): One fervent vote against Wintergreen. Mimeograph.
2. Brams, S.J. (1977): When is it advantageous to cast a negative vote? In: Mathematical Economics and Game Theory: Essays in Honor of Oscar Morgenstern (R. Henn, O. Moeschlin, eds.). Springer, Berlin, pp. 564–572.
3. Felsenthal, D.S. (1989): On combining approval with disapproval voting. Behavioral Science 34, 56–70.
4. Daniel Ferguson & Theodore Lowi (2001): Reforming American Electoral Politics: Let’s Take“No” for an Answer, 34 PS: Pol. Sci. & Pol. 277, 277
5. George C. Leef (October 29, 2004) A Modest Proposal – Let’s Allow Negative Voting 
   http://fff.org/explore-freedom/article/modest-proposal-lets-negative-voting/
6. Michael Kang(2010): Voting as veto,  Michigan Law Review, Vol. 108, No. 7

Internet discussion forums
http://www.researchgate.net/post/Has_anyone_ever_tried_Negative_Votes
http://opengov.ideascale.com/a/dtd/Ability-to-vote--No--against-a-candidate./2912-4049
https://frozengarlic.wordpress.com/2015/03/05/negative-voting/#comment-6296
https://www.facebook.com/groups/NegativeVote/

d as of 2015.3.2