On Closed P-Sets with ccc in the Space omega*. - Rvszard Frankiewicz; Saharon Shelah; Pawel Zbierski (J. Symb. Log., 1993)

On Herbrand consistency in weak arithmetic. - Zofia Adamowicz; Pawel Zbierski (Arch. Math. Log., 2001)

On complexity reduction of Sigma1 formulas. - Zofia Adamowicz; Pawel Zbierski (Arch. Math. Log., 2003)