cocolib is under GPL3 with an additional request: if you make use of the library or the command line tool in any form in a scientific publication, please refer to and cite the paper

  author  = {B. Goldluecke and E. Strekalovskiy and D. Cremers},
  title   = {The natural vectorial total variation which arises from geometric measure theory},
  journal = {SIAM Journal on Imaging Sciences},
  volume  = 5,
  number  = 2,
  pages   = {537--563},
  year    = {2012},

where the library is first mentioned officially.

If you make use of the light field suite, please also refer to the web page and cite

  author  = {S. Wanner and B. Goldluecke},
  title   = {Variational Light Field Analysis for Disparity Estimation and Super-Resolution},
  journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence},
  volume  = {36},
  number  = {3},
  pages   = {606--619},
  year    = {2014},

You should also cite the appropriate papers when using specific models and algorithms, see the feature list and references.