Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
strongly [ˈstrɔŋlɪ] adv (construct) кре́пко; (push, defend, believe) си́льно
I feel strongly about it во мне э́то вызыва́ет си́льные эмо́ции
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.