this one last fall and have been working away at it for a few months. The first half of the book (which went more quickly for me) is excerpts from Primary sources in the history of UCCan liturgy/worship. The second half is excerpts from secondary sources in the same area.
I found this to be a very worthwhile book. Maybe not a "must read" but very worthwhile. The various sources give one a feel for how worship was being discussed over the years. And the introductory blurbs Kervin puts before each one were quite helpful. Then Kervin finishes with a concluding essay that I personally found would have been very worthwhile as a standalone piece.
I do recommend this book. But I think a non-worship oriented book is called for next.