Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
muster [ˈmʌstər] vt (support, energy) собира́ть (собра́ть*perf) (troops) набира́ть (набра́ть*perf) (also: muster up)(strength, courage) набира́ться (набра́ться*perf) +gen
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.