One of the well known relational bibliometric methods is the co-word analysis. The co-occurrence of words can be illustrated in a matrix. By the means of various mathematical methods like cluster analysis and others the matrix can be illustrated in a two-dimensional science-map that represents a well structured rendition of information. The key question of this paper is how can different objects e.g. key-words and authors or institutions be linked by co-word analysis. In bibliographic documents key-words, authors and institutions are elements of each document. Thus we can talk of a direct linkage between these objects according to the joint occur in one document. The properties of one author to appear with certain keywords in certain articles allows a linkage over the documents. Indirect linkage can be found if documents, raised from the connection between authors and key-words, are eliminated in the functional relationship and new networks are generated which show an indirect linkage of authors on the basis of keywords. This paper will show a method how different networks can be linked directly and indirectly by using co-word analysis. The combination of content maps by co-word analysis will be shown using a technology monitoring concerning fuel cells.