`  Dear Melcombe,  Thanks you for your welcolme, your useful links and your answer.  My understanding of the later is that my points are valid (questions one can ask, answers not in article, answers in the external website) but that the explanations look like textbook, they are ``how to`` (calculate) material, and thus should not belong to Wikipedia but rather to some Wiki etc.  I can understand that, even if I would advocate that Wikipedia could give some further explanations/example when a subject is complex. For example, an article that helped me a lot when studying for the CFA exam is http://en.wikipedia.org/wiki/Bond_duration. And this article displays a short proof/explanation for the modififed duration.  What's more, I do believe that, even if Wikipedia should keep to an introductional level, it still could/should offer some further reading leads. As a case in point, programming articles usually provides in depth examples and links to detailed implementations  (http://en.wikipedia.org/wiki/Factory_method_pattern etc.)  Best Regards, Philippe   `