PB Van der Wal, C Nagel, HR Voordes… - … Suppl., Vol. 6, p. 131, 1972 - adsabs.harvard.edu
… the eclipsing binaries: QS Aqi, EG Cep, FZ Del, AK Her, LS Her and EW Lyr. The suspected
eclipsing binary … A secondary minimum can be seen 0.5 periods after the primary minimum, …