EPA abstracts are available from 1969, EPB from 1974, and EPC and EPD from 1983.

Advanced use A space between keywords has the effect of an 'and' operator, and will produce results containing all the supplied keywords. The operator 'OR' between two keywords will match one or both keywords. Parentheses may be used for more complex searches. Search will attempt to match all standard variants of a word (plurals, gerunds etc). Double quotation marks around an expression will perform an exact search for that expression. All searches are case insensitive. Examples:
urban planning will match documents containing both 'urban' and 'planning' (as well as 'plan', 'plans', etc).
urban or planning will match documents containing either 'urban' or 'planning'.
(urban or town) planning will match documents containing either 'urban' and 'planning', or 'town' and 'planning'.
"urban planning" (ie within double quotes) will match only the string 'urban planning'.