How to give a credit to the sources on the Internet in an acceptable way? I am a PhD student in mathematics. It happens to me that many times I see some very good mathematical ideas on the Internet and my research is influenced by these ideas. In general, the Internet sources are not considered as reliable and therefore not widely accepted in the academic circles. However, mathematics is self-verifiable and one can verify the feasibility of the ideas and the veracity of the claims.

I could try to find other references to the published articles and documents to reference them instead in my research. But why should I do that? Is that not a form of lying and a suppression of the credit where it should be due? My ideas were really influenced by the sources on the Internet not by the related references and I would like to give the credit there. How should I do this in an acceptable way?
How should you cite?
There is a format for citing web references for nearly any citation style.
In the MLA format

Last, First M. “Article Title.”Website Title. Website Publisher, Date Month Year Published. Web. Date Month Year Accessed.

In APA style

Author, A. (date). Title of document [Format description]. Retrieved from Website

You may leave out the author field when it is not possible to retrace the original author (as described here)
When should you cite?
If you were to refer a material that has sufficient information to be given credit for your work, then by all means you ought to cite it. But first, try to find the roots of the idea, if such idea has been published elsewhere before this web-page was published. On-line content is highly susceptible to contain plagiarized content. See if you could locate the original source. If found, cite the original source instead.