Encyclopedias and handbooks are another good source for finding more general, background information on a topic, as well as lists of key research and review articles for further reading.
Because of their large collections of computer science and engineering reference works, the best starting place for ECE is probably Springer, which you can search by full text and then limit the results to reference work entries. The Springer electrical engineering reference works include the Encyclopedia of Robotics, Handbook of Antenna Technologies, Encyclopedia of Systems and Control, Springer Handbook of Electronic and Photonic Materials, Handbook of Optical Fibers, Encyclopedia of Machine Learning and Data Mining, Handbook of Digital Games and Entertainment Technologies, Handbook of Image Processing and Computer Vision, Springer Handbook of Robotics, Handbook of Unmanned Aerial Vehicles, Handbook of Organic Light-Emitting Diodes, and Semiconductor Physics.
You can also search Wiley and Elsevier (Science Direct) directly, then limit your results to reference works or encyclopedias..
Some others to try, depending on your topics: