Abstract: The cross sections for three initial-state radiation processes, e+e-→π+π-J/ψ, π+π-ψ(2S), and K+K-J/ψ have been measured between threshold and s= 5.5 GeV, using data on and off the Υ(4S) resonance collected with the Belle detector at KEKB. The Y(4260) and Y(4360) observed by the BaBar collaboration are confirmed, and the resonance parameters improved. Two new resonant structures, the Y(4008) and Y(4660) have been observed for the first time. There are no known vector charmonium states that match these new observations, which must be either new charmonium states or charmonium hybrids, or are produced via other dynamics.