Today marks the 13th day of the Omer, which begins the second day of passover and ends the night before Shavu’ot, lasting a total of 49 days. Spiritually, it’s a time for reconstruction and preparation for blessings to come. I personally recommend this book because it provides a detailed step by step guide for each of the 49 days. (“The counting of the omer” written by Rabbi Simon Jacobson)