I understand you are looking for books on spoken communications; however, could you be more specific. I work with many ESL students to assist them in transcending their fears of public speaking as well as developing spoken communication skills.
If you could clarify your answer a bit, that would be helpful. Are you referring to public speaking, presentation skills, personal communications within your family, how to communicate effectively with employers, co-workers or staff members, etc.
I am writing a series of books on effective communicatins. The first is titled "31 Tips to becoming an Effective Presenter." You can learn from reading books, but the only way to improve your spoken communications is by doing it. I would strongly suggest in joining Toastmasters (www.toastmasters.org), a worldwide organization stressing communications and leadership skills. Not only that, but this organization will develop self-esteem, confidence and can be a life-altering experience.
One tip I have, particularly if English is a 2nd language, is to concentrate on the message and make it simple. Many ESL students I have in my class are concerned with developing their English vocabulary and reducing their accents. Both of these are important; however, the message is most important. You should used SIMPLE vocabulary regardless if English is your primary or secondary language (the reason is explained in another book I'm publishing). And don't worry all that much about an accent. If you don't rush through your talk and you are deliberate and you slow down, the accent is not critical. Again, reducing one's accent is important, but not critical. Just remember to sloooow down and focus on your message.