Beckerman, M., & Boghossian, P. (Eds.). (2021). Classical Music. Open Book Publishers. 

This collection on classical music through the twenty-first century grabs insight from leading composers, academics, journalists, administrators and more. Gain knowledge on music traditions, challenges, and scope. This collection is split into two parts, the first giving analysis on issues of classical music to present day regarding diversity, governance, and perception. The second part brings case studies from all over the world regarding how organizations have responded to the challenges brought up in the first part. This resource brings music into perspective, the social aspects of it, and how time can change everything. This book includes biographical references and index. This resource would be used well for any student wanting a contemporary idea on classical music.

https://doi.org/10.11647/obp.0242 

"An invaluable guide for lovers of classical music designed to enhance their enjoyment of the core orchestral repertoire from 1700 to 1950" (Yale University Press, 2018). Find details and explore well-known works from sixty-eight composers. This book avoids using technical terminology, making it a great place to start for beginners or for those who may have less of a musical background. Organized alphabetically, follow along and listen to these timeless pieces and receive background on these engaging composers. Suitable for young adults and above. Philip is a broadcaster, scholar, and musician himself.

https://doi.org/10.12987/9780300242720 

This book is an overview of the lives of great composers. Many greats from the classical era, Beethoven, Mozart, Haydn, etc. are included. There are biographical chapters on these composers, some photographs, and reflections on musicological findings. This source is a great go to since you have many composers in one place. Schonberg is an American music critic and author. He has many books about different composers and critiques of pieces. This book originally published in 1970 was last updated in 1997 with additions of new composers.  The Lives of the Great Composers is at an adult reading level.