Complex sentence: After the war much of the collection was returned to the library, however a substantial number of volumes which had been sent for storage in the eastern part of the country were never recovered, with upwards of 350,000 volumes destroyed and a further 300,000 missing.
Split into simpler sentences: After the war much of the collection was returned to the library. However, a substantial number of volumes which had been sent for storage in the eastern part of the country were never recovered, with upwards of 350,000 volumes destroyed and a further 300,000 missing.