Logical connection between the structural organization of the studied classifications' elements and their essential (ideological) content was proved and illustrated. There were provided analysis and were revealed peculiarities of the scientific principles and the principles of bibliographic organization of information through the prism of content (qualitative) and semantic (quantitative) constituents of systematization, in particular: hierarchical, tetralogical principle, atomism, decimal meaning, coincidence of opposites, convolution/deployment, deism, dynamism, division, rational perception, emanation, subordination on the one hand and alphabetical, concentration principle, integration, decimality, consistency, encyclopedic ability, extensibility, versatility, mnemonic ability, internationalism, multidimensionality, scientific, logic, stability, description, conglomeration, regularity, systematization from the other hand. There was summarized the experience of predecessors, engaged in the study, design and implementation of library-bibliographic classification systems in the context of development of sciences classifications, and it was also proved that previous research, focused on the analysis of classification systems, was related to the study of library catalogues' organization in which a quantitative structural component of the library classification was taken for basis, but systematization as a scientific category of essential and knowledge organization of information was not considered. It was defined and analyzed the facts of structural and logical availability with essential and ideological features of classification systems' organization in the context of systematization, such as: a quadromeaning, fasetizing, hierarchy and decimality. The complex explanation of necessity and probability of optimization in system is described and unification and harmonization of processes in area related to the information organization is given as well. Prospects of the development approaches and mechanisms for classification of information as a basic direction of documentary scientific study are outlined, nevertheless, it was proved that the structure of the classification system does not affect the content of the latter, as it is appropriate to the dynamic of knowledge, but its "artificiality" is only applies to the contents, therefore a comprehensive indexing of information resources of the UDC tables in Ukraine is absolutely possible. The content of some concepts is specified, in particular: "content" is a quantitative (formal) characteristic of semantic and syntactic classification components; "richness of content" is a meaningful (cognitive) characteristic of its semantic and syntactic components; "conglomeration" is a process of collections formation, which consists of various IRL, preserving all its principles of indexing for the consolidated presentation of notations of indexing, i.e. combining the potential of different IRL preserving their main features and properties; "folkindexing" is a public index or indexing by means of collective mind; "regularity" is a structural characterization of system, which is formed as the result of information systematics, when there is no clear subordination, and system formation is provided by the regularity of components; "Systematyzatsiynist" (the hierarchic characteristic of the system) is a structural characteristic of the system, which consists of the hierarchical set of elements, and connections between them express subordination to each other; "Systemnist" (the linear characteristic of the system) is a principle of classification formation, in accordance to which the classification acquires certain structural characteristics and transforms directly into the system of classification. In general, the results of the thesis research allowed to present library bibliographic classifications not just from the position of functional cell organization of the library catalogues, but first of all from the point of view of these classifications' significance in provision of the documentary systematization implementation processes through the prism of historically conditioned link between the evolution of sciences classifications and library-bibliographic classification systems. Thus, the classification systems of bibliographic information occupy a prominent place among the other possible mechanisms of the library systematization of scientific information, specifying scientism and validity of richness of bibliographic information content. Therefore bibliography as a science, along with the library science, belongs to the established field of socio-cultural activity, and amounts a much broader area of cognizance that contains all branches of knowledge which are anyhow presented by means of library-bibliographic classification systems with a projection on classification of sciences, because knowledge is the classified information.