On surfaces with conical singularities of arbitrary angle
  The geometry of closed surfaces equipped with a Euclidean metric with finitely many conical points of arbitrary angle is studied. The main result is that the set of closed geodesics is dense in the space of geodesics. 
Charalampos Charitos, Ioannis Papadoperakis, Georgios Tsapogas
math.GT math.MG