Depending on the database, coverage is generally from the 1970's to present. Compendex Web contains citations and abstracts from over 2,500 journals, conference proceedings, reports, and other publications in the fields of engineering and technology including agricultural engineering . Coverage is from 1980 to the present. AgNIC Database List is a list of agriculture-related information systems, databases, and datasets compiled by the National Agricultural Library's Agriculture Network Information Center. InSite 2 provides full text access to articles from a vast array of periodicals, from popular and technology magazines to scholarly journals of international renown.
Coverage is the last five years.
WorldCat provides descriptions for 32 million books, journals, magazines, and other materials published worldwide. It is a database of the catalog records from most US academic libraries.