Perhaps you should try some spelling variations:
"imaginary unit" » "imaginary i", "imaginary bci", "imaginary hair"
"imaginary part" » "imaginary early"
"imaginary axis" » "imaginary parts", "imaginary monies", "imaginary places"
"imaginary 2" » "imaginary _", "imaginary 3"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((((("imaginary unit") OR ("imaginary part"))) OR ("imaginary 2"))) OR ("imaginary axis")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"imaginary unit\") OR (\"imaginary part\"))) or (\"imaginary 2\"))) or (\"imaginary axis\"))".
• Removing quotes may allow a broader search: (((((( imaginary unit ) OR ( imaginary part ))) or ( imaginary 2 ))) or ( imaginary axis )).
• Adding a wildcard symbol may retrieve word variants: (((((("imaginary unit") OR ("imaginary part"))) or ("imaginary 2"))) or ("imaginary axis"))*.