Are the two colored raven cards the only way to change the seasons?

dh098017 said:

No, there are also the Crown of Winter, Crown of Azor Ahai, and Crown of Meereen that can make it Winter or Summer. Carrion Bird, Ill Tidings, and The Raven's Song can also get rid of the black and white ravens if you are looking for ways to change the season away from summer/winter.....

Nope, there are 3 other attachments that can change the season:

• Crown of Winter (stark unique only) makes it winter if the black raven isn't in play
• Crown of Meereen (targaryen unique only) makes it summer if the white raven isn't in play
• Crown of Azor Ahai (baratheon unique only) makes it summer or winter if the opposite raven isn't in play (you choose by kneeling the crown or not)

The first 2 have additional effects, but none modify income like the ravens do.