Declarative and operational in knowledge based systems. - M. Popper; Milos Hauskrecht (MIE, 1991)

The operational aspects of object-oriented approach in medical expert systems design. - J. Stanek; M. Popper; Milos Hauskrecht (MIE, 1991)

From Low-level to High-level Operations in Expert Systems. - M. Popper (DEXA, 1993)