Sinners' Prayers by Joseph Dearing
This 24-page booklet is a good supplement to Soulwinning Crash Course.
It explains and defends the application of Romans 10:9-13 to salvation, while also reproving the abuse of Romans 10:9-13.
It's a concise yet multifaceted study.
A must-have for pastors, sunday school teachers, soulwinners, tract-authors, Christian parents, and anyone who has ever doubted their salvation because of confusion surrounding this topic.