I would trust Disneyland.com (8-11 during the week in the middle of July) as the most reliable since it is the official Disney web site. The others may be basing their hours on historic information (last year, I think the hours were 8-12 most of the summer). Disneyland.com, although not always up-to-date on other things is usually pretty up-to-date on its hours. However, they may choose to extend the hours based upon crowds. Like most things, hours are subject to change.
PS -- Keep checking back with Disneyland.com for the latest hours.