Instruct: Classify the given review into positive or negative sentiment.
Query: Essential discography

An excellent discography that fills a gap in music research. These bands represent the ground between country music and swing and are direct forerunners of rock and roll. While most hot string bands are here, it would have been nice to see Leo Soileau's various groups and the Alley Boys of Abbeville included. But maybe that indicates just how rich this field is. Great job.