https://catalogobiblioteca.ingemmet.gob.pe/cgi-bin/koha/opac-search.pl?q=ccl=an%3A527%20and%20itype%3ACAPL%20and%20au%3AEchtler%2C%20Helmut%20P.%20and%20au%3AOncken%2C%20Onno&format=rss2 Search results for 'an:527 and itype:CAPL and au:Echtler, Helmut P. and au:Oncken, Onno' at Biblioteca - Ingemmet 0 20