One of DW's trademarks was the detailed research he did for his novels, and this began with 'The Forbidden Territory'. According to Blackwells catalogue of his library, which they disposed of after his death, he used four books from his library to prepare himself for writing the book. Two of them are illustrated here.
For some later books he was to use over twenty books from his personal library for his research.
The depth of DW's research was so great, and it was used so convincingly, as to prompt one journalist to assume at the launch party that DW had lived in Russia himself.