PETRUȘEL, A. Book Reviews: “John R. Graef, Johnny Henderson, Abdelghani Ouahab; Topological Methods for Differential Equations and Inclusions”, CRC Press, Taylor & Francis Group, Boca Raton, FL, USA, 2019, Xiv + 360 pp., ISBN 9781138332294 - CAT# K393112. Stud. Univ. Babeş-Bolyai Math. 2020, 65, 161-162.