The Anchor Bible Dictionary entry for the book of Isaiah.
"Isaiah, Book of," Anchor Yale Bible Dictionary A-Z volume 3 (Yale University Press: New Haven, 1992), 472-488
The tradition-critical approach of von Rad operates with broader form-critical assumptions about the role of the prophet vis å vis the literature. Isaiah's adaptations of Israel's tradition come in the form of public address, akin to preaching. First Isaiah (1-39) contains this preaching, but it cannot everywhere be simply identified with this preaching, either in neat chronological order, or thematic presentation, or even haphazard arrangement. Von Rad does see some rough chronological movement in the present book, and one might well assume that early chapters are related to events in the days of Ahaz (5-12), later chapters to the days of Hezekiah (28-39). Still, critical judgments are required about the historical events of Isaiah's day, and canons of literary analysis help to determine consistent patterns in Isaiah's own speech. What falls outside either of these areas is clearly secondary and editorially supplied. It would be fair to conclude that von Rad's primary area of interest lay in interpreting the theological significance of those portions of First Isaiah which could reasonably be traced to the historical prophet, using the methods of form- and tradition-criticism. Von Rad remained vitally interested in the prophet Isaiah, as a man of history theologically actualizing Israel's traditions. But this Isaiah could not be simply read off the top of the text; it required highly sophisticated literary and historical tools to lay him bare.