All tracks from Girls Planet 999 – Creation Mission: 2021년 41주차 Download Chart[Week 41 of 2021 Download Chart]. Gaon Chart (in Korean). Archived from the original on October 14, 2021. Retrieved October 19, 2021.
Kim, Min-ji (May 30, 2024). "케플러, 마시로·강예서 제외 7인 재계약...활동 연장 [공식]"[Kep1er, 7 members, minus Mashiro and Yeseo, renewed their contracts... to extend activity [Official]]. News1. Archived from the original on May 30, 2024. Retrieved May 30, 2024– via Naver.
Kim, Ji-ho (July 16, 2024). 케플러, 9인 체제 종료...강예서·마시로, 아름다운 이별[Kep1er, 9-person system ends... Kang Ye-seo and Mashiro, beautiful farewell] (in Korean). Dispatch. Archived from the original on July 15, 2024. Retrieved July 16, 2024– via Naver.
Han, Jae-hoon (July 15, 2025). 케플러 영은, 건강 문제로 8월 컴백 활동 불참[Kep1er Yeoung-eun will not participate in August comeback activities due to health issues.]. Sports World. Retrieved August 6, 2025– via Naver.
Kim, Jin-seok (June 13, 2022). "'20일 데뷔' 라필루스, 데뷔곡은 '힛야!(Hit Ya!)'"['Debut on the 20th' Lapillus , debut song 'Hit Ya!'] (in Korean). JTBC. Archived from the original on June 17, 2022. Retrieved June 17, 2022– via Naver.
All tracks from Girls Planet 999 – Creation Mission: 2021년 41주차 Download Chart[Week 41 of 2021 Download Chart]. Gaon Chart (in Korean). Archived from the original on October 14, 2021. Retrieved October 19, 2021.
Kim, Min-ji (May 30, 2024). "케플러, 마시로·강예서 제외 7인 재계약...활동 연장 [공식]"[Kep1er, 7 members, minus Mashiro and Yeseo, renewed their contracts... to extend activity [Official]]. News1. Archived from the original on May 30, 2024. Retrieved May 30, 2024– via Naver.
Kim, Ji-ho (July 16, 2024). 케플러, 9인 체제 종료...강예서·마시로, 아름다운 이별[Kep1er, 9-person system ends... Kang Ye-seo and Mashiro, beautiful farewell] (in Korean). Dispatch. Archived from the original on July 15, 2024. Retrieved July 16, 2024– via Naver.
Kim, Jin-seok (June 13, 2022). "'20일 데뷔' 라필루스, 데뷔곡은 '힛야!(Hit Ya!)'"['Debut on the 20th' Lapillus , debut song 'Hit Ya!'] (in Korean). JTBC. Archived from the original on June 17, 2022. Retrieved June 17, 2022– via Naver.