Once one of the three dominant forces of the recording industry (along with Victor and Columbia, during the 20s), Brunswick started by making phonographs.
Acquiring Vocalion in 1924, it flourished and was sold to Warner Bros. in April 1930. Shortly after, it quickly changed hands from Warner to ARC, then to Decca (for its British branch), then finally Columbia in 1939, which disbanded it in 1940, only to be revived by Decca again in 1944, which used it until 1968 to issue its records in the UK. In 1970, it spun-off but became dormant in 1981 (sunk into some legal nightmares).
Nowadays the pre-1957 Brunswick catalog era is controlled by Universal, via Decca, and is actually managed by Verve, while Tarnopol controls the 1957-1970 period. The latter is the actual Brunswick, distributed by Koch Entertainment.
Records in the 10000 series (10-inch) and 30000 series (12-inch) are single-sided. 1 Records in the 10100 series are double-sided.