Serdega, V., and G. Ivanovs. “Refraction Seasonal Variation and That Influence on to GHz Range Microwaves Availability”.
Elektronika Ir Elektrotechnika
, vol. 78, no. 6, July 2007, pp. 39-42, https://eejournal.ktu.lt/index.php/elt/article/view/10812.