If you are using an entry from a well-known encyclopedia and the listings are alphabetical, you don't need to give volume and page numbers.
If you are using an entry from an encyclopedia that is updated frequently with new editions, you can leave out the publication information like city and publisher but include the edition and year.
Some words have many meanings. If you are citing one of many entries for the same word (mechanic), you must indicate which entry you're using.
You must also state whether the source is a printed version or an online version.
