Recently manuals of industrial products become large and often consist of separated volumes. In reading such individual but related manuals, we must consider the relation among segments, which contain explanations of sequences of operation. In this paper, we propose methods for linking relevant segments in hypertext authoring of a set of related manuals. Our method is based on the similarity calculation between two segments. Our experimental results show that the proposed method improves both recall and precision comparing with the conventional tf. idf based method.