Handbook of the Psychology of Aging Book

For some reason, this book seems to be quite popular in the Middle East as the go-to source when one wants to learn about the psychology of crowds; however, I found very little science and plenty of the author's personal opinions and observations -which have not been systematically studied nor confirmed- with a dash of racism, sexism, and elitism on the side (I guess that should be expected, given that The Crowd is quite out-dated).

That it is not to say that it is completely worthless; it's not. First of all, Le Bon's writing is engaging, and several passages struck me as beautifully written and eloquent. And there are arguments and assertions that I think are likely to be true, such as people being impressed more with prestige and exaggerated, passionate statements rather than with rational arguments.
On a funny note, Le Bon maintains that mental illness, or "madness" is catching, so you might want to cross-reference what you read.

If I were to sum up my thoughts on this, I would say read it for the insightful observations that it offers, but not as a credible source with regards to the psychology of crowds. Scientifically robust and updated works should be sought instead.