A neural network for solving the travelling salesman problem on the basis of city adjacency in the tour. - Aart Joppe; Helmut R. A. Cardon; Jan C. Bioch (IJCNN, 1990)

Key Issues for Successful Industrial Neural-Network Applications: an Application in Geology. - Helmut R. A. Cardon; R. van Hoogstraten (Artificial Neural Networks, 1995)