The short Dulles piece on the joint declaration is here: http://www.firstthings.com/article/1999/12/two-languages-of-salvation-the-lutheran-catholic-joint-declaration
I should mention that Dulles's last few paragraphs seem very weak to me. It is written for a popular audience, but some of the problems might be with Dulles' own formation and thought. "Scholasticism" is somehow one (and only one?) among many different "thought forms," and Lutheranism an incompatible "thought form." He doesn't show much knowledge of Luther or later generations of Lutherans. Luther himself could and did write like a scholastic, but in my opinion he just wasn't very good at it. Maybe Dulles is comparing Luther's more popular works with more scholastic Catholic theological works, and doesn't have in mind Protestant Orthodoxy. But there are also a host of Catholic popular works from the time.
Chris Malloy has a lot of material, including a whole book on the topic of the joint declaration: Hisbook is at https://www.amazon.com/Engrafted-Christ-American-University-Studies/dp/0820474088
See also his:
"The Nature of Justifying Grace: A Lacuna in the Joint Declaration" The Thomist 65 (2001): 93–120.
There is a piece on Thomas More on Luther on Justification: http://www.thomasmorestudies.org/docs/Angelicum90pages761-98.pdf
Then there is: "Sola salus, Or Fides caritate formata: The Premised Promise of Luther's Dilemma" Fides Catholica 2 (2008): 375-432.
For my own understanding of Luther, I personally have profited greatly from non-Catholic authors. For a general account of 16th century theories, see Alister E. McGrath, Iustitia Dei: AHistory of the Christian Doctrine of Justification. 2nd ed. For Luther’s relationship to Thomism in particular, see “Luther Among the Thomists,” in David Steinmetz’s Luther in Context. I am personally indebted to the late Steinmetz, who was a great figure in the study of the 16th-century. His Luther and Staupitz has fascinating material on his early development. For Luther himself, Steinmetz recommended Heiko Oberman’s Luther: Man between God and the Devil. I also have found helpful Bernhard Lohse’s Martin Luther’s Theology: Its Historical and Systematic Development. Again, none of these sources are Catholic, but I think that they are helpful for someone with an appropriate Catholic background. Steinmetz was frustrated because he said that now even many Catholic theologians and theology students don't know enough Catholic theology to distinguish their own position (or different Catholic positions) from those of the Reformers.