C13−C18\mathrm{C}_{13}-\mathrm{C}_{18}C13−C18
C11−C13\mathrm{C}_{11}-\mathrm{C}_{13}C11−C13
C12−C18\mathrm{C}_{12}-\mathrm{C}_{18}C12−C18
C11−C16C_{11}-C_{16}C11−C16