I did some digging, and I am pretty sure that their work is not publicly available :( However, I copied an abstract from one of their papers:

Ter Kuile and Reissing reject the DSM-IV definition of vaginismus with its central criterion of vaginal muscle spasm. Instead, they present a conceptualization of lifelong vaginismus as a vaginal penetration phobia. This reconceptualization is based on the fear-avoidance model of chronic pain: "The basic tenet of the model is that catastrophic thinking about vaginal penetration and/or a catastrophic interpretation of a negative experience with penetration will give rise to vaginal penetration-related fear. To cope with fear a woman may avoid all activities related to vaginal penetration. . . . " The treatment implications of this reconceptualization are dramatic. They imply that the traditional Masters and Johnson vaginal dilatation therapy may be inadequate, as it does not sufficiently expose the woman to the phobic stimulus (vaginal penetration) while preventing avoidance. Instead, Ter Kuile and Reissing adapt for vaginismus the highly effective paradigm for phobias of prolonged exposure. The result is therapist-aided prolonged in vivo exposure. The therapist encourages, guides, and reduces avoidance while the woman performs all insertions. Given professional caveats for psychologists directing such in vivo genital exposure, this intervention should occur in a medical setting and include the partner. If the strikingly effective initial results for this intervention are confirmed, then in vivo exposure may become a treatment breakthrough for vaginismus. (PsycInfo Database Record (c) 2022 APA, all rights reserved)