Forecasting of development of national economy by mathematical modelling : the subject-matter of the issue prepared during the researchvisit in Italy, sponsered by Consigilo Nazionale delle Ricerche and presented on the conference held at the Scientific Centre of the Polish Academy of Sciences in Rome, on 24 March 1976 / Lech Kruś. - Kruś, Lech (1945- ). (Conferenze e Studi - Accademia Polacca delle Scienze, 1979)