Projective Beth Property in Extensions of Grzegorczyk Logic.

Larisa Maksimova Projective Beth Property in Extensions of Grzegorczyk Logic. 365-391 2006 83 Studia Logica 1-3 http://dx.doi.org/10.1007/s11225-006-8309-1 db/journals/sLogica/sLogica83.html#Maksimova06a