Various publishers, 6 hardcover volumes, 1919-1961
As to Being Reformed explains why Kuiper left the CRC in the early 1920's, only to return a few years later, and covers his appreciation of the 3 Points of Common Grace, and of his view of the future of the CRC having adopted those points.
While the Bridegroom Tarries is a collection of sermons Kuiper preached on end-time living during WWI.
To Be or Not to Be Reformed is Kuiper's view of the external and internal threats facing the CRC in 1959, shortly after his retirement from the presidency of Calvin Seminary after the 2nd Common Grace controversy had purged the faculty.
The other titles are studies of evangelism/missions, the atonement, and the church.
3 volumes with names; To Be or Not to Be Reformed is an ex-church library copy; The jacket for God-Centered Evangelism is worn; the jacket for For Whom Did Christ Die? is good.