While articles and monographs which focus specifically on the Letters to Timothy and Titus are easily found, some aspect of the letters may be helpfully treated as a distinct subsection in a larger work, and the larger work is such that one might not suspect work on the Pastorals exists in it. A list of over sixty works of that nature are provided at the link below. Works where the title or topic would make it almost inevitable that significant engagement with the Pastorals would be involved — say, church offices in the NT, widows in the NT, or the role of women in the church according to the NT — are largely excluded. For purposes of this post, we’ve limited ourselves to listing English-language scholarship.
The list is accessible here.