Reference:
  Author: Andrew J. Page and Ben Taylor and Aidan J. Delaney and Jorge Soares and Torsten Seemann and Jacqueline A. Keane and Simon R. Harris 
  Title: "SNP-sites: rapid efficient extraction of SNPs from multi-FASTA alignments"
  Journal: bioRxiv
  Year: 2016
  DOI: 10.1101/038190
  URL: http://biorxiv.org/content/early/2016/01/29/038190.full-text.pdf+html 
  eprint: http://biorxiv.org/content/early/2016/01/29/038190.full.pdf
