Here is a picture of the Rubicon in winter, when Julius Caesar crossed it. No idea if this is the same river.
Our modern sources for this episode include:
And our ancient sources include:
Plutarch’s Parallel Lives (Bernadotte Perrin translation):
Suetonius’ Twelve Caesars: Life of Caesar (J.C. Rolfe translation)
Cassius Dio’s Roman History (Earnest Cary translation)
Appian’s Gallic War (Horace White translation)