Complex sentence: Wibberley published, under his name and also three pen-names, over one hundred books, but is best known for his four satirical novels about the imaginary country Grand Fenwick, particularly for the first of these- "The Mouse That Roared".
Split into simpler sentences: Wibberley published, under his name and also three pen-names, over one hundred books. He is best known for four satirical novels about an imaginary country Grand Fenwick--particularly for the first of these, "The Mouse That Roared".