Perhaps you should try some spelling variations:
"michael theory author" » "michell theory author", "michael gregory author", "michael thos author"
"michael heller author" » "michael goller author", "michael muller author", "michael hall author", "michael feller author", "michael helme author", "michael miller author"

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: (("michael theory author") OR ("michael heller author"))*.
• Removing quotes may allow a broader search: (( michael theory author ) or ( michael heller author ))*.