“The book under review presents a comprehensive and meticulously structured exploration of strong and weak solutions concerning regular oblique derivative problems for second-order elliptic equations. Its systematic approach and detailed examination of boundary singularities make it a valuable resource for researchers and practitioners in various fields … . Its comprehensive treatment, structured approach, and detailed analysis make it an indispensable resource for postgraduates and young researchers seeking to deepen their understanding of elliptic equations within conical domains.” (Giuseppe Di Fazio, zbMATH 1532.35001, 2024)