Urban Sketchers em Lisboa is the book on the 2011 Lisbon Symposium that was held on 21-23 July 2011.
This 252 hardcover is written in both Portuguese (I think) and English. The English title is 'Urban Sketchers in Lisbon - drawing the city'.
It collects essays on sketching, experiences of the instructors, the workshops conducted and the sketches made by attendees.
Workshops make up the bulk of the content. There are many sketching exercises to try. The lessons are not technical, they don't talk about drawing techniques, but more on ideas you can explore while sketching. For example, Nina Johansson's workshop is about using several quick or unfinished sketches to form a narrative. Other workshops explore contrast and complementary, improving observational skills, understanding perspective in the real world, etc.
Sketches of the attendees are included after every workshop. There are many interesting styles to check out. They are printed a bit small but I think it's the right size as most of them look quite rushed.
It's a rather pricey book selling for USD $44 in Portugal, $50 in Europe and $58 in other countries. Shipping is pretty quick.
The book is sold on the Urban Sketchers blog.