“…A noteworthy contribution is that of Webb and Infante [49], who provided an elegant theory for studying all manner of nonlocal boundary conditions. Other interesting contributions have come from Anderson [2], Cabada, Infante, and Tojo, [7, 8], Cianciaruso, Infante, and Pietramala [10], Goodrich [17, 18], Graef and Webb [27], Infante [29], Infante and Pietramala [30–35], Jankowski [36], Karakostas and Tsamatos [37, 38], Karakostas [39], Webb [47], Webb and Infante [48, 50], and Yang [53–57]. The classical papers by Picone [43] and Whyburn [51] are interesting as concerns the original developments of differential equations with nonlocal elements.…”