The free energy of the two-dimensional dilute Bose gas. I. Lower bound
A. Deuchert, S. Mayer, R. Seiringer, Forum of Mathematics, Sigma 8 (2020).

The free energy of the two-dimensional dilute Bose gas. II. Upper bound
S. Mayer, R. Seiringer, Journal of Mathematical Physics 61 (2020).

The free energy of a dilute two-dimensional Bose gas
S. Mayer, The Free Energy of a Dilute Two-Dimensional Bose Gas, Institute of Science and Technology Austria, 2020.

The free energy of the two-dimensional dilute Bose gas. I. Lower bound
A. Deuchert, S. Mayer, R. Seiringer, ArXiv (n.d.).