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The group has continued to meet regularly since the publication of the last bulletin and has welcomed a number of new members and visitors from both home and overseas. Many members who joined at the beginning or very early on in the Group's history still attend regularly, but several long‐standing members have also left, or ceased active participation, in the period under review. Towards the end of 1972 Mr Wells relinquished the chairmanship of the Group, due to pressure of work, and his place was taken by Mr Mills. Another departure, and one that robbed the Group of one of its most active and forceful members, was that of Jason Farradane. He left the country in 1974, and the Group presented him with a book as a memento of many enjoyable and provocative discussions stimulated by his presence at the meetings which he unfailingly attended. It was with great pleasure that he was welcomed back to a meeting while he was visiting this country in January 1976.

The term ‘obsolescence’ occurs frequently in the literature of librarianship and information science. In numerous papers we are told how most published literature becomes obsolete within a measurable time, and that an item receives half the uses it will ever receive (‘half‐life’) in a few years. ‘Obsolescence’ is however very rarely defined, and its validity, interest, and practical value are often assumed rather than explained. Before reviewing studies on ‘obsolescence’, therefore, it is necessary to look at the concept and to identify the reasons why it should be of interest.

IThe activity of the group has continued to progress with great energy and enthusiasm for practical applications of the theoretical ideas and schemes of the members, many of whom have acted as consultants to private, government and international institutions. Some of the longer‐serving members retired, but continued to attend meetings. The Group heard with great regret of the death of Mr B. I. Palmer, its Founder Chairman. An important element in the discussions from its beginning was the theoretical scheme of S. R. Ranganathan, and this was largely due to Palmer, who had returned from war service in India fired with enthusiasm for Ranganathan's ideas, and determined to interest others in developing and applying them. His collaboration with Mr A. J. Wells, another founder member, had as an early result their little monograph, The fundamentals of library classification, which has greatly influenced both teaching and practice of classification, and not only in Britain.

In 1974, citations to the literature of an earlier year, say 1966, will be to a relatively small number of ‘enduring’ articles, the remainder having been forgotten. The currently cited literature of a particular growing subject will consist of the ‘enduring’ literature of earlier years, and the recent literature some of which will endure and some of which will ‘die’. There willl be more citations to recent literature because there is more of it. A trend towards multiple authorship may be reducing the growth rate of published articles.

The use per issue‐day of recent issues of 125 periodicals on open access at the Science Reference Library (SRL) has been studied for over four months. There is statistical evidence for the expected separate phase within ‘updating’ of ‘current awareness scanning’ of issues which have arrived since the reader's last visit to the library: its half‐life of two to three months reflects the pattern of reader‐visit frequencies rather than any characteristics of the literature. The isolated uses of issues of periodicals, representing a part of ‘following up searches’, showed no significant relation between use and age. The irregular monographic and conference series, with their unpredictable dates of arrival at the shelf, were not subject to current awareness scanning. Of the regular periodicals in the two chemical technologies, ‘magazines’ were more heavily used than ‘journals’ and, as expected, issues in the English language more heavily than those in foreign languages: these differences were less marked in chemical sciences than in chemical technologies. The results include figures for the variances of use data. These were so high as to suggest that lists of periodical titles ranked by use per issue data are of very little value in critical decisions between one little used title and another. Differences in rank, resulting from a difference of less than fifteen uses obtained from less than five monthly surveys, are unlikely to be significant. Ranking by use per title instead of by use per issue (or equivalent) tends to arrange journals in size order.

In a paper published in 1973 Oromaner included an analysis of citations to articles in three sociological journals in 1960 by subsequent volumes of those journals 1961–70. This study was unusual in that it was one of very few that followed citations to a given set of articles through in time (diachronous study), as opposed to analysing by date a set of references to articles made by journals or articles of a given date (synchronous study) — a far more common procedure.

The Science Reference Library Classification was developed during the middle of the 1960s as a scheme to arrange books on the shelves of a large open‐access library integrating the whole of Science and Technology in a single collection. It is intended to help in the retrieval of information which is not indexed elsewhere, by abstracting and bibliographic services, and to make ‘browsing’ by the large number of readers (one‐third, according to the National Libraries Committee report) who enter the library without a specific reference in mind as fruitful as possible.

In one of his two letters published in the June issue of Journal of Documentation, Moss rightly draws attention to the confusion arising out of the casual use of terminology in the field of information storage and retrieval. Unfortunately he does not go far enough, for there is a great deal of sorting out to be done with regard to our understanding of what we are talking about when we discuss languages, vocabularies, etc. before we start assigning names to the concepts which emerge. Moss's suggested terms are no more helpful in connoting the attributes of the things we are trying to isolate than those which he criticizes, and Bhatta‐charyya's reply (published with ref. 1) is a poor argument for retaining expressions which are clearly unsatisfactory. Leaving aside the problems arising out of retrieval of texts using such terminology, we have difficulty in knowing what authors are talking about when we read such documents, and the context and explanations in the text have to be used to enable us to appreciate what is being discussed. Bhattacharyya has had two papers published quite recently in which such lack of clarity appears, the first being that on ‘natural language’, of which Moss is critical, the other that on ‘explicit relations’.

Over several decades many ranking techniques have been proposed as aids to journal selection by libraries. We review those closely related to physics and others with novel features. There are three main methods of ranking: citation analysis, use or user judgement, and size or ‘productivity’. Citations offer an ‘unobtrusive’ quantitative measure, but not only is the absolute value of a citation in question, but also there is no consensus on a ‘correct’ way to choose the citing journals, nor of the ranking parameter. Citations can, however, point out anomalies and show the changing status of journals over the years. Use and user judgement also employ several alternative methods. These are in the main of limited applicability outside the specific user group in question. There is greater ‘parochialism’ in ‘use’ ranking than in ‘judged value’ lists, with citation lists the most international. In some cases, the attempted ‘quantification’ of subjective judgement will be misleading. Size and productivity rankings are normally concerned with one or other formulation of the Bradford distribution. Since the distribution is not universally valid, for library use the librarian must satisfy him/herself that the collection conforms to the distribution, or that his users would be well served by one that did. This may require considerable effort, and statistics gained will then render the Bradford distribution redundant.

The 1960s saw the birth of what is now called “scientometrics”. One of the queries that arose then related to citations of previous literature. Was recent literature cited proportionately more than older literature? Studies by Price, along with that reprinted here, seemed to indicate that the answer was “yes”. This “immediacy effect”, as it was labelled, could be measured in quantitative terms, but how to do so required some thought. For example, what was the best form of index for representing immediacy, and what errors were involved in estimating the effect? Discussions of the usage of past literature could have practical implications for libraries. One question, therefore, was what implications, if any, citation studies had for the provision of journals to library users. On the scientometrics side, there were such questions as why an immediacy effect occurred and to what extent it could be discerned in different subject areas. This article surveys attempts to examine questions like these over the period from the 1960s to the present day, updating an article published in Journal of Documentation in 1967.