I will review Owada Tetsuo's Oda Nobunaga Otoko no Miryoku sometime next month. I bought the book at Book-Off earlier this week. The book was published in 1991 and was written as a supplement for the following year NHK Tiaga drama Oda Nobunaga.
Here is a nice quote about Nobunaga in Sources of Japanese Tradition Volume 1, p. 303. This sums up Nobunaga nicely.
"Nobunaga had schooled himself in self-reliance, alertness, and adaptability, and he looked for these qualities in his men, prizing those who could act without orders and granting them the utmost freedom of action."
Tenka no tame! Nobunaga no tame!