Beyond popular and basic reference tools, there are many other tools that can assist those with more specialized needs. These resources are more aca-
demic in nature, and the Invisible Web abounds with them, from propri- etary databases to fee-based resources that cover in depth almost any sub- ject area, especially in the sciences. Subscription databases that cover one subject rather than serving as general-purpose research tools fall into this layer of the Invisible Web. Examples include services such as Elsevier’s Sci- enceDirect; CINAHL, a medical database for Nursing and Allied Health stu- dents; and ERIC—Education Resources Information Center, which is avail- able both through subscription and as an open-access database. This second layer of Invisible Web resources also includes subject-based search engines, academic periodical collections, and image collections. Here is a selection.
WorldWideScience.org: the global Science gateWay
http://worldwidescience.org
This database is the product of an alliance among international scientific institutions and is operated by the United States Department of Energy. It can be searched in many languages and offers translations. It also offers a list of all the institutional collections included and is a focused federated tool that searches across all of these holdings. Searches may also be limited to specific collections. A regular search produces references with author, title, and collection where the document resides. Full text is offered for many but not all documents. The materials offered include conference papers, articles, and other documents not readily found on the surface web. Tags: federated
search, real-time search, unique resources not found or linked to elsewhere
neW york PUblic library digital gallery
http://digitalgallery.nypl.org
This image collection offers digitized copies of the many rare and unusual holdings of the New York Public Library, including historical documents, images, photographs, art pieces, maps, and more. The collection covers all subject areas with over 700,000 images that can be searched by key- word or browsed by subject. Items can be printed out or the user can order high-quality reproductions. The library indicates clearly that some images may require copyright approval for use, but it supplies all the information needed to secure that approval. This site can help with history assignments or may be useful to anyone seeking historical images. Tags: unique materials
deePdyve
www.deepdyve.com
DeepDyve, a fee-based resource sponsored by a private company of the same name, offers access to articles and journals. DeepDyve states that its goal is to serve people who are unaffiliated with institutions. It can be searched for content as a database and returns results with author, title, source, a line about the purpose of the article, and the cost to access. Hold- ings can also be browsed by subject, journal title, and publisher. Selecting a journal title brings up all of its contents by volume and issue including the full run of many titles. Access to an article lasts seven days. Printing is limited to selected publishers. Fee-based resources are, by definition, part of the Invisible Web. Tags: dynamic content, fee-based
doaJ: directory oF oPen acceSS JoUrnalS
www.doaj.org
This resource offers access to full-text articles from online scholarly publi- cations covering all subjects. While it calls itself a directory, DOAJ is really a database of articles that can be searched using keywords. A browsing option permits users to search journals by subject area or to go directly to specific titles. The collection includes titles from many countries. The website includes a statement about the selection criteria, which favor research and scientific publications. DOAJ is maintained by Lund University in Lund, Sweden; the service is financed by sponsors and members. Many of the journals and arti- cles represented in DOAJ may be found using Google Scholar, but here they are presented in an organized and easily accessed manner. The ability to see a whole collection of scholarly titles at once through the directory is an advan- tage that brings this tool into the Invisible Web family. Tags: dynamic content
baSe—bieleFeld acadeMic Search engine
www.base-search.net
BASE is sponsored by the Bielefeld University Library in Bielefeld, Germany. This fine search engine has the specific goal of covering material not read- ily found by commercial search engines. It seeks to include “intellectually selected resources” that meet academic quality standards and “web resources of the ‘Deep Web,’ which are ignored by commercial search engines or get lost in the vast quantity of hits.” Materials searched include over 30 million documents in several languages. Options include full-text, author, title, and subject searches. The collection can also be browsed by Dewey Decimal Clas-
sification (DDC) or document type. Searches can then be refined by author, subject, DDC, year of publication, language, content provider, and document type. The search record includes all this information as well as URLs, publish- ers, journal names, and other descriptive information. Tags: unique resources
not found or linked to elsewhere
techxtra: engineering, MatheMaticS, and coMPUting
www.techxtra.ac.uk
TechXtra is a free service that, according to the site, focuses on “articles, books, the best websites, the latest industry news, job announcements, technical reports, technical data, full text e-prints, the latest research, the- sis [sic] & dissertations, teaching and learning resources and more, in engi- neering, mathematics and computing.” Developed and sponsored by Heriot Watt University, in Edinburgh, Scotland, TechXtra states that it searches parts of the web that Google does not or, as they describe it, the “Hidden Web.” TechXtra lists the collections that it searches relevant to engineering, mathematics, and computing, including content from over fifty publishers and providers. Basic and advanced keyword searching are available. Search produces a list of resources identifying how many items were found by col- lection and indicating whether full text is available. Selecting a resource result brings up specific information: title and author information, abstract, and a link to full text. TechXtra always lists clearly whether full text is avail- able and, if not, provides a link to the publisher’s site for purchase if that is desired. Where full text is not available through TechXtra, users may be able to get access through the subscription-based services for which their institution has already paid. Users can also go directly to individual collec- tions/resources to find descriptions of resources and links. Extras include guides, industry reports, and job leads. Tags: unique resources not found or
linked to elsewhere, vertical
citeSeerx
http://citeseerx.ist.psu.edu
Sponsored by the College of Information Sciences and Technology at Penn- sylvania State University, CiteSeerX is a search engine that concentrates on computer and information science literature. It also provides resources on algorithms, data, metadata, services, techniques, and software that can be used to promote digital libraries. The user can search under documents,
authors, and tables. Search results offer titles, source, authors, abstract, year, and number of times that the document has been cited by the other resources in the database. The users can click on the cited-by references to see those resources as well. Clicking on the title brings up an abstract, a list of citations used in the document, and link to full text. An author search brings up name and number of citations in CiteSeerX with links to doc- uments. A table search locates documents with tabular information on a topic, then provides the usual linking information. The nature of the con- tent makes this an Invisible Web tool. Tags: unique resources not found or
linked to elsewhere
Scitation
http://scitation.aip.org
Sponsored by the American Institute of Physics, the world’s largest pub- lisher of physics journals, this database offers all things physics. The jour- nals can be browsed by title, publisher, and subject category. Keyword searching is also available, as are advanced searching capabilities. Browsing titles brings up listings, links, and availability of full text. Most journals are open access but a limited number of titles are freely available only to mem- bers/subscribers; however, anyone can purchase articles from those pub- lications. The site also offers professional services such as a MyScitation feature and current-awareness services that alert users to newly published information. Users can find some of the individual publications on the web if they know what to look for. What Scitation provides is indexing across many publications at once, including fee-based Invisible Web resources.
Tags: fee-based, unique resources not found or linked to elsewhere
citeUlike: everyone’S library
www.citeulike.org
CiteULike is a social bookmarking site sponsored by Oversity Ltd., a British company. It labels itself as intended for the collection of “scholarly refer- ences.” Users can become members of the CiteULike community and use it to organize and maintain their bookmarks. However, even nonmembers can search the references to get leads to articles about a subject. The articles are linked and identified by who posted them and when. They become a sort of recommendations list that might appeal to some researchers; because the references are linked, CiteULike functions also as a resource discovery tool. It is not a search engine; its results lists are the product of a community
building resources. The search results may be findable elsewhere, but with- out the unique community endorsement. Tags: unique material not found or
linked to elsewhere