En Eski Jeff Keller kitaplarını, en eski Jeff Keller sözleri ve alıntılarını, en eski Jeff Keller yazarlarını, en eski Jeff Keller yorumları ve incelemelerini 1000Kitap'ta bulabilirsiniz.
What this power is I cannot say; all I know is that it exists and it becomes available only when a man is in that state of mind in which he knows exactly what he wants and is fully determined not to quit until he finds it.
— Alexander Graham Bell