First contact remarks on umbra difference calculus references streams
  The reference links to the modern classical umbral calculus before that known as blissardian symbolic method are numerous. Rota founded and then extended finite operator calculus has links to references which are plenty numerous. The references via links to the difference q calculus umbra way treaded or without even referring to umbra are giant numerous. These reference links now result in counting in thousands the relevant papers .   The purpose of the present attempt is to offer one of the keys to enter the world of those thousands of references. 
A.K.Kwasniewski