Supervised learning with quantum-enhanced feature spaces, Vojtech Havlíček, Antonio D. Córcoles, Kristan Temme, Aram W. Harrow, Abhinav Kandala, Jerry M. Chow, and Jay M. Gambetta, 2019Nature, Vol. 567 (Nature Portfolio)DOI: 10.1038/s41586-019-0980-2 - A foundational paper introducing a widely used quantum feature map and demonstrating quantum kernel-based classification on near-term quantum hardware, detailing the overlap method for kernel estimation.
Quantum Machine Learning, Maria Schuld, Francesco Petruccione, 2018 (Springer)DOI: 10.1007/978-3-319-96424-9 - A textbook covering the theoretical foundations and algorithms of quantum machine learning, including explanations of quantum kernel methods and their estimation.
Quantum Kernel Estimation, Qiskit Developers, 2025 (IBM Quantum) - An official tutorial from a leading quantum computing framework, illustrating the practical implementation of quantum kernel estimation, including the overlap method, with code examples and explanations.