Greetings. I am a researcher currently developing a study on the measurement of difficulty/complexity in electronic circuits. I am looking for books, scientific articles, instructional materials, or datasets that present sets of electronic circuits accompanied by some indication of difficulty, complexity level, or pedagogical classification, even if such indication is subjective or approximate. Any reference would be welcome, including classic textbooks, lecture notes, datasets, academic repositories, or materials used in technical or university-level education. If you are aware of works that organize circuits by difficulty level, or that could be used as a basis for comparative analysis, I would greatly appreciate your help and recommendations. On my ResearchGate profile, I have published some works on complexity measurement in other domains, such as industrial property patents and C programming language source code, which may help contextualize my research approach. Thank you in advance for any help or references you may be able to share.
