Looks like System Trader Success is mentioned as a favored website by the Author of this new book entitled, “Anatomy of $SPY on First Trading Day of the Month“. Appears the book is an in-depth study of SPY on the first trading day of the month. I just ordered a copy. Here is the text from Amazon describing the book.
Anatomy of $SPY on First Trading Day of the Month takes the most compelling edges from the past and combines them with greatly detailed new analysis. Over 75 pages in length, the book provides incredibly comprehensive detail on First Trading Day of the Month market behavior and probabilities. Kora Reddy shows where the greatest trading edges lie through detailed historical analysis. Day and swing traders alike will be able to use the guide to take advantage of historical probabilities, around First Trading Day of the Month.