Period variations the intermediate polars EX Hya, FO Aqr and RXS   J180340.0+401214
  We present results of CCD photometric study of the intermediate polars FO Aqr, EX Hya and RXS J180340.0+401214 = USNO-A2.0 1275-09738647 and corresponding corrected ephemerids. 
Vitalii V. Breus, Ivan L. Andronov, Tibor Hegedus, Pavol A. Dubovsky,   Igor Kudzej, Karol Petrik, Stanis{\l}aw Zo{\l}a
astro-ph.SR astro-ph.GA