Complex sentence: Mulroney had been criticized in 1976 for lacking policy depth and substance, a weakness he addressed by making several major speeches across the country in the early 1980s, which were collected into a book, "Where I Stand", published in 1983.
Split into simpler sentences: Mulroney had been criticized in 1976 for lacking policy depth and substance. He addressed that weakness by making several major speeches across the country in the early 1980s, and collected them into a book, "Where I Stand", published in 1983.