Click on the "Trade skills - by trade" link on the column to the left here, then on "Engineering" - it will give you a list of all the schematics available and what level is required. Clicking on the schematic will tell you where it is dropped, quested for, or bought. If there is no schematic listed under the name, it can be learned from a trainer.
Alternatively, type "schematic" in the search window to the left - this will bring up a list of all the schematics and who sells or drops them, and scrolling over the schematic will tell you what level and branch you have to be to use it.
Edited, Thu Mar 16 13:23:49 2006 by fledarmus