Two books that are intended as introductions to the Risorgimento are Risorgimento: The History of Italy from Napoleon to Nation State by Lucy Riall and the second edition of The Risorgimento and the Unification of Italy by Derek Beales. Both books are roughly chronological surveys of the various steps towards Italian unification. Denis Mack Smith's biographies of Cavour and Mazzini are also good introductions into the period in question from the vantage point of two individual leaders. Clara Lovett's The Democratic Movement in Italy, 1830-1876 examines the successes and shortcomings of the unification process.