if((NOT ${DISABLE_HWM14}) OR (NOT DEFINED DISABLE_HWM14))
    set(SOURCES ${SOURCES}
    external/hwm/hwm14.f90
    )
endif()

if((NOT ${DISABLE_NRLMSIS}) OR (NOT DEFINED DISABLE_NRLMSIS))
    set(SOURCES ${SOURCES}
    external/nrlmsis2/alt2gph.F90
    external/nrlmsis2/msis_constants.F90
    external/nrlmsis2/msis_init.F90
    external/nrlmsis2/msis_gfn.F90
    external/nrlmsis2/msis_tfn.F90
    external/nrlmsis2/msis_dfn.F90
    external/nrlmsis2/msis_calc.F90
    external/nrlmsis2/nrlmsis2Wrapper.F90
    )
endif()
