, 1999a, "Doing things with words" and the law, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 311-321.
, 1999b, Directive discourse, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 295-310.
, 1999c, Directives, norms, and performatives, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 323-344.
, 1999d, Directives, optatives, and value statements, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 263-293.
, 1999e, Internal and external integration of the study of law, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 99-120.
, 1999f, Law and politics in time and space, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 121-135.
, 1999g, Norm and conduct, the problem of the "fulfilment" of the norm, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 255-261.
, 1999h, On the logical-semantic structure of directives, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 233-254.
, 1999i, Philosophy of law and social philosophy, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 169-180.
, 1999j, Present status of legal philosophy, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 137-152.
, 1999k, Selected papers in legal philosophy, Springer, Dordrecht.
, 1999l, Some problems of the theory of norms, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 181-200.
, 1999m, State and law: an attempt at integration of the juristic with the sociological approach, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 63-76.
, 1999n, The "general science of law": main approaches and their history, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 15-30.
, 1999o, The complexity of law and of the methods of its study, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 49-62.
, 1999p, The concept of "positive law", in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 153-167.
, 1999q, The peculiarities of the study of law and the question of integration, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 31-48.
, 1999r, The problem of "directive meaning", in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 201-215.
, 1999s, The problem of the existence of the norm, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 217-231.
, 1999t, The problem of the validity of law, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 77-89.
, 1999u, The rule of law and natural law, in K. Opałek, Selected papers in legal philosophy, Dordrecht, Springer, pp. 91-98.