Rank two Cohen-Macaulay modules over singularities of type   $x_1^3+x_2^3+x_3^3+x_4^3$
  We describe, by matrix factorizations, all the rank two maximal Cohen-Macaulay modules over singularities of type $x_1^3+x_2^3+x_3^3+x_4^3$. 
Corina Baciu, Viviana Ene, Gerhard Pfister, Dorin Popescu