Ostensible or apparent authority which negatives the existence of actual authority is merely a form of estoppel, indeed, it has been termed agency by estoppel, and you cannot call in aid an estoppel unless you have three ingredients: (i) a representation, (ii) a reliance on the representation, and (iii) an alteration of your position resulting from such reliance.

However the book recommended books including other materials are as follows 1. Chapter ‌‌‍‌‌‍‍‍‌‍‍‌‍‍‍‌‌‌‍11 page 303 of Ewan Macintyre Business Law, (Ninth Edition) Pearson, 2. Academic Journals 3. Articles. 4. Law chambers, 5. Any books on Business Law. THANK YOU‌‌‍‌‌‍‍‍‌‍‍‌‍‍‍‌‌‌‍.