The present invention provides methods of fracturing high temperature subterranean zones and viscous aqueous foamed fracturing fluids therefor. These compounds inhibit tubulin polymerization andor target vasculature and are useful for treating proliferative disorders, such as cancer. Accordingly, an amount of oil may be uniformly maintained in each of the plurality of compressors to prevent losses due to friction andor increases in power consumption due to a lack of oil in one or more of the compressors. By using the heterocyclic compounds, organic light-emitting devices having high efficiency, low driving voltage, high brightness, and long lifespan may be prepared.