About phase transitions in Bose gases at constant density and constant   pressure
  The phase transitions in Bose gases at constant volume and constant pressure are considered. New results for the chemical potential, the effective Landau-Ginzburg free energy and the equation of state of the Bose condensate in ideal Bose gases with a general form of the energy spectrum are presented. Unresolved problems are discussed. 
Velin G. Ivanov, Dimo I. Uzunov