TY - ECHAP AU - Alexander Brown CY - Berlin, Heidelberg DO - 10.1007/3-540-18653-0_173 M1 - Lecture Notes in Physics PB - Springer Berlin Heidelberg PP - Berlin, Heidelberg PY - 1987 SN - 978-3-540-18653-3 SP - 466 EP - 468 TI - Chromospheric variability mechanisms affecting pre-main sequence stars VL - 291 ER -