Kaleidoscopical Configurations in G-Spaces. - Taras O. Banakh; Oleksandr Petrenko; Igor Protasov; Sergiy Slobodianiuk (Electron. J. Comb., 2012)

Thin Ultrafilters. - Oleksandr Petrenko; I. V. Protasov (Notre Dame J. Formal Log., 2012)

Selective and Ramsey Ultrafilters on G-spaces. - Oleksandr Petrenko; Igor Protasov (Notre Dame J. Formal Log., 2017)