The publication you have in your hands is a condensed publication of the text book with the same title and by the same author, Marian G. Berry:

I have published various books that deal with events of the end of time, as these have been declared by the profetic Scripture in the Holy Bible. The profetic Scripture usually expresses itself in figurative language, that can be frustrating until the time of its fufillment is at hand. The book "Warning in the 1260, 1290 y 1335 day timelines of Daniel 12" is based in a comparative search of the profetic Scripture made by me and over the interpretation in the writings of the profetic expositor, Ellen G. White. You will find many references to the writings of Mrs. White in this publication, in addition to references from other sources.

In the introduction of her most widely known work titled "The Great Controversy," Mrs. White describes her life’s long work as follows:

"...in this time of peril the followers of Christ are to bear to the world the warning of the Lord’s second advent; and a people are to be prepared to stand before Him at His coming, "without spot, and blameless." (2 Pedro 3:14)...Through the illumination of the Holy Spirit, the scenes of the long-continued conflict between good and evil have been opened to the writer of these pages. From time to time I have been permitted to behold the working, in different ages, of the great controversy between Christ, the Prince of life, the Author of our salvation, and Satan, the prince of evil, the author of sin…In the great final conflict, Satan will employ the same policy, manifest the same spirit, and work for the same end as in all preceding ages. That which has been, will be, except that the coming struggle will be marked with a terrible intensity such as the world has never witnessed…As the Spirit of God has opened to my mind the great truths of His word, and the scennes of the past and the future, I have been bidden to make known to others that which as thus been revealed—to trace the history of the controversy in past ages, and especially so to present it as to shed a light on the fast-approaching struggle of the future." The Great Controversy, Introduction, pag. x, xi