A modern adaptation of several old catechisms; contains 52 questions and answers, accompanied by online resources; the children’s answers have also been set to music; available as an app
Books for Using Historical Theology in Bible Study
Resources for Studying Haggai in the Light of Historical Theology
When looking at doctrines of systematic theology taught in Haggai, I recommend using Historical Theology by Allison. He treats the same subjects in the same order Wayne Grudem follows in the first edition of his Systematic Theology, which makes this a companion volume.
Also, the Ancient Commentary on Christian Scripture includes a volume on The Twelve Prophets, which includes Haggai.