Ishida Volume 2

One-Space High Approach  

"This move 2 has a much briefer history than the small knight approach move. While occasionally seen in pre-modern games, it did not become a standard move, due to its lack of emphasis on territory. In modern times it has been re-evaluated and is now just as popular as the knight's move. In modern Go, with its preoccupation with speed and influence, the true virtues of this move have been discovered, bringing an added dimension of depth and strength to the fuseki."

• The 5-3 Point (I won't repeat myself - check this link :-)

With the three most standard replies:

3-4 point approach  

"Because of its solidity and stability, 2 is regarded as the standard approach move to the 5-3 stone." (Volume 2 part five)

High approach  

"White plays the high approach move 2 to prevent Black from gaining influence by pressing down on him. In the local context, however, this move entails a loss as White must abandon profit in the corner." (Volume 2 part six)

Entering at the 3-3 point  

"The primary objective of White 2 is to take secure profit before Black and, if circumstances permit, to get sente. A favorable ladder is desirable for this move." (Volume 2 part seven)

By the way, the ladder referred to arises as follows:

The ladder should favor white  

"It is only commonsense that one must consider the ladder when the sequence to is played. The moves to form a standard pattern but White gets an inferior result if the ladder favors Black."

--DaveSigaty