Devotion to the Immaculate Heart of Mary and devotion to the Sacred Heart of Jesus are companions in the hearts of the faithful. The Immaculate Heart of Mary leads us to her Son and purifies our prayers to him in her perfect love.
Resources for learning more:
True Devotion to Mary by St. Louis de Montfort (trans. by Frederick William Faber, 1863). Catholic Way Publishing, 2012.
The Admirable Heart of Mary by St. John Eudes. Buffalo, NY: Immaculate Heart Publications (licensed from Loreto Publications, 2008).
Fatima for Today by Fr. Andrew Apostoli. Ignatius Press, 2010.