Perhaps you should try some spelling variations:
"imaginary unit" » "imaginary part", "imaginary i", "imaginary bci"
"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 2"))) OR ("imaginary axis")).
• Removing quotes may allow a broader search: (((( imaginary unit ) or ( imaginary 2 ))) or ( imaginary axis )).
• Adding a wildcard symbol may retrieve word variants: (((("imaginary unit") or ("imaginary 2"))) or ("imaginary axis"))*.