He scrolled to the end of the PDF to see who had fixed the legend’s work. There was no name, only a final note on the last page:
The book is structured to provide a single, comprehensive source for designing versatile op-amp circuits. Its key sections include: Fundamentals
Operational amplifiers are high-gain differential amplifiers that amplify the voltage difference between two input terminals. They are commonly used in feedback configurations to achieve specific circuit functions, such as amplification, filtering, and impedance transformation. The design of op-amp circuits requires a thorough understanding of op-amp theory, circuit analysis, and practical implementation.