id	keyword
esrj-74108	radon
esrj-74108	soil
esrj-74108	radon concentration
esrj-74108	lima
esrj-74108	gas
esrj-74108	gas radon
esrj-74108	city
esrj-74108	period
esrj-74108	rivers
esrj-74108	rocks
esrj-74108	soil radon
esrj-74108	et al
esrj-74108	rímac
esrj-74108	measurements
esrj-74108	chillón
esrj-74108	soil gas
esrj-74108	hole
esrj-74108	average
esrj-74108	concentrations
esrj-74108	area
esrj-74108	lima city