These are some websites with useful general information on microphones
and recording techniques, which is a bit hard to find between all the
websites that sell them.
The 'g' links point to Google to find them in case the url changes.
with an electronic booklet on
microphones [zipped text file], that explains how condenser,
electret, moving-coil, and ribbon microphones work, how directional
characteristics are obtained and how phantom powering works.
(g)