Ei5LC & Ei4KU
How to build a HF Rhombic Antenna
Research and PhD thesis by Christina Arras about Sporadic-E
A link to Paul O'Kane's contest logging software: SD by EI5DI, runs well with 'wineconsole' for linux.
An older issue of the Antennenbuch, by Karl Rothammel (Silent Key Y21BK)