Retrospective literature searches

Of course, from time to time, librarians also will produce bibliographies on topics of interest. This is a particular challenge in computer engineering where a subject compilation can be out of date as soon as it is published, but it is certainly useful for retrospective literature searching. This is certainly evident with the older compilations listed below ... 

The other and perhaps more important function of an abstract journal is to permit retrospective literature searches. To ensure this, an abstract journal must be complete, that is to say it must review all publications which may contain information of interest... 

Collective indexes are an invaluable tool in a retrospective literature search as they eliminate the repetition of identical steps which would be necessary when using the appropriate volume indexes, and at the same time they offer simultaneous access to several million abstracts. For the first time the Ninth CA Collective Index with its 57 volumes and 20 million entries was recorded as the largest index in the world by the Guinness Book of Records. It is far surpassed by the Twelfth Collective Index with a total of 115 volumes published in 1992. All collective indexes are published also on microfiche and microfilm. 

If a retrospective literature search is to be carried out back to the beginning of Chemical Abstracts, the searcher must be somewhat familiar with the nomenclature rules and substance names used at that time, as there was no Index Guide and no internal cross-references before 1946. Up to the fourth collective period (1946) the substitution positions were designated by letters ortho-, para-, meta-Y>os ons) (Fig. 60) rather than numbers. In addition, the abstract numbers were written in a different form at that time, e.g. the reference to Vol. 40 2189 in the fourth collective index. 

Contemporary science, particularly the biosciences, is afflicted by a flood of information that can only be coped with by focusing one s interests and exploiting modern methods of literature searching. literature searches are essentially of two types retrospective, and current awareness. In the former case, searches will usually be based on printed or CD-stored versions of commercial information services in the latter, computer-based literature searches are the method of choice. 

A better way to obtain the information we seek is to use chemical literature databases. Several such databases exist. These resources can be used for retrospective searches of mentions of any given program, vendor, method, or other term. It is also highly fitting to use a computerized technique (database searching) in our study of computational chemistry. 

However, retrieval services cater for both current-awareness and retrospective search needs. Whilst computerised document retrieval services are useful for current awareness, there has been much activity to apply computer techniques to actual information retrieval, particularly for retrospective searching. This has taken the form of setting up specialised data banks for numeric and structurail information. These are a form of secondary service but are more closely related to handbooks and encyclopaedias than to abstract publications. (Data handbooks, etc., are sometimes referred to as tertiary sources, but since secondary sources are guides to the primary, the term tertiary sources is more accurately applied to guides to the secondary literature s).)... 

We have already seen that numeric data banks exist primarily for retrospective searching. What is therefore required in those where numeric data consitute the basic file, is to record the most reliable values in the system. In other words a critical evaluation is really required, prior to input to the system. The promotion of such evaluations is an area where Codata is particularly active. Furthermore, particular values may be determined repetitively and one wishes to record only the best value. This may mean replacing a value with a later, more accurate one, so the facility to do this must be built into the system. Finally, primary data gathered from the literature may be transformed in some way or used to calculate secondary data which can also be stored. Examples are the Information Centre for Mineral Thermodynamics in Grenoble 22), which uses primary thermodynamic data to calculate other thermodynamic functions, and the Online Data Bank on Atomic and Molecular Physics at Belfast which is working on the automatic transformation and development of relations between different data sets. This last points the way towards exciting future developments in dynamic, as opposed to static, data banks. 

We have seen that there are essentially three different kinds of information in the chemical literature — (1) numerical, (2) conceptual, (3) structural. Computerised retrieval from the primary literature is as yet embryonic, and we must therefore turn om attention mainly to secondary sources. The normal secondary sources deal largely with words, t. e. conceptual information, the other typ>es of information being dealt with by specialised systems. Computer search services therefore use machine-readable versions of the standard sources for cmrent-awareness, specialised systems being used for retrospective searching. 

The literature before 1967 is included retrospectively in the database CAOLD, which, in the meantime, contains 700,000 references to 1.4 million substances, which were mentioned before 1967, and 152.000 references to patents. For this database Chemical Abstracts Service scans bit by bit the Formula Index of the Sixth (1957-1961) and the Seventh (1962-1966) Collective Period. Therefore only substance references are contained in this database with no text information or even abstracts. However, cross-references to patents are marked with P. Using this database you have to consider that the chemical nomenclature in those days was quite different to the names in use today. Therefore an online search in CAOLD should be proceded by a search in the Registry File (Sect. 7.6) and then continued with the appropriate CAS Registry Number in CAOLD. 

Searching in the CA file automatically includes the years since 1967. A search in printed services will require the repetition of the search steps for every new volume, or for every new collective period, when conducting a retrospective search - a very time-consuming procedure. Anyhow it is unavoidable in the case when literature from before 1967 has to be examined (Sect. 2.7). 

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