“…It is worth mentioning above all the works Behr [2][3][4][5]. Semenoff [6,7] Reed [8], Hoskins [9], Kiekeben [10], Green [11,12], Howard [13,14] and Bǿegh [15]. Since then, in many European countries (including Norway, Belgium, the Netherlands, Spain, France, Germany and Great Britain), intensive work has been underway to develop and improve these techniques.…”