I'm reading Impagliazzo and Wigderson's famous $\mathsf P=\mathsf{BPP}$ paper in 1997. Since I'm new to this field and the paper is a concise conference version, I have difficulty following their proofs. In particular, some of their new theorems lack proofs. To my best knowledge there hasn't been a journal version published.
I'm looking for resources from which I can learn their result, preferably those with formal proofs. I'd be very grateful if you could tell me about such resources.