Rather than type separately all of the metadata elements that make up a citation, you may be able to get the Citation_Information from a bibligraphic database. For USGS publications, that database is the USGS Publications Warehouse. Here's how you can do this for USGS publications:
Guess. The general form is serYYYYNNNN, where ser is an abbreviation of the publication series, YYYY is the two- or four-digit year of publication, and NNNN is the report number within the series, without leading zeros.
Series abbreviations include
Search the publications warehouse to find the citation page
of the publication you want. The identifier is the last part of that
page's URL. For example, searching USGS Publications Warehouse for "Porphyry Copper deposits of the world" will yield a
record for Open-File Report 2008-1155; in the upper right corner of the
Publication Citation, there is a link labeled "Bookmark this citation";
it ends with the identifier ofr20081155.
When you have the identifier, you can use Tkme to paste that information into your metadata in the appropriate place. The slide show below shows you the steps to do that: