The Internet Guide to shortwave radio is a great source of information which is available on-line on the subject.

I have a copy of this document here but you probably should look at the latest version.

Transmitter Documentation Project The source for info on shortwave transmitters. The shortwave transmitter database. Info on the world's shortwave radio transmitters.

DX-Antverp is oldest Belgium club of shortwave listeners.

ILG - free comprehensive up-to-date database of shortwave, mediumwave and FM stations around the world. A source of information you must have! Best to use in conjunction with ERGO receiver control and propagation software.