Guide to information sources

A Guide to information sources (or a bibliographic guide, a literature guide, a guide to reference materials, a subject gateway, etc.) is a kind of metabibliography. Ideally it is not just a listing of bibliographies, reference works and other information sources, but more like a textbook introducing users to the information sources in a given field (in general).
Such guides may have many different forms: Comprehensive or highly selective, printed or electronic sources, annotated listings or written chapters etc.
Functions.
Often used as curriculum tools for bibliographic instruction, the guides help library users find materials or help those unfamiliar with a discipline understand the key sources.
Examples.
Aby, Stephen H., Nalen, James & Fielding, Lori (2005). Sociology; a guide to reference and information sources. 3rd ed. Westport, Conn.: Libraries Unlimited.
Adams, Stephen R. (2005). "Information Sources in Patents"; 2nd ed. (Guides to Information Sources). München: K. G. Saur 
Blewett, Daniel K (2008). American military history; a guide to reference and information sources. 2nd ed. Westport, CT : Libraries Unlimited.
Jacoby, JoAnn & Kibbee, Josephine Z. (2007). Cultural anthropology; a guide to reference and information sources. 2nd ed. Westport, Conn.: Libraries Unlimited.
Schmidt, Diane & Bell, George H. (2003). Guide to reference and information sources in the zoological sciences. Westport, Conn. : Libraries Unlimited.
O'Hare, Christine (2007). "Business Information Sources". London: Library Assn Pub Ltd
Ostwald, W (1919). Die chemische Literatur und die Organisation der Wissenschaft. Leipzig : W. Ostwald & C. Drucker. (This is considered the first "guide to information sources").
Stebbins, Leslie F. (2006). Student guide to research in the digital age; how to locate and evaluate information sources. Westport, Conn.: Libraries Unlimited.
Webb, W. H. et al. (Ed.). (1986). Sources of information in the social sciences. A Guide to the literature. 3. ed. Chicago : American Library Association.
Zell, Hans M. (ed.). (2003). The African studies companion; a guide to information sources. 3rd rev. and expanded ed. Glais Bheinn : Hans Zell.