“zorro” in Dicionario de Dicionarios do galego medieval, SLI - ILGA 2006–2022.
“zorro” in Xavier Varela Barreiro & Xavier Gómez Guinovart: Corpus Xelmírez - Corpus lingüístico da Galicia medieval. SLI / Grupo TALG / ILG, 2006-2016.
“zorro” in Dicionario de Dicionarios da lingua galega, SLI - ILGA 2006-2013.
"zorro" in Tesouro informatizado da lingua galega. Santiago: ILG.
2012, A History of the Spanish Lexicon: A Linguistic PerspectiveISBN0199541140, page 39: "The initial attestations of Sp. zorro/zorra 'fox' are from the mid fifteenth century and appear almost exclusively in the feminine, employed in cancionero poetry, with reference to idle, immoral women (cf. mod. zorra 'prostitute'). […] DCECH may well be right in stating that zorro/zorra secondarily became a euphemistic designation for the dreaded fox (cf. raposo so used). […] The late initial documentation of zorro leads to the question [of] whether this word goes back to early Roman Spain or whether it is a later borrowing from Basque, a derivation, as noted above, challenged by Trask (1997: 421). Far from convincing is the unprovable hypothesis in DCECH that zorro goes back to a verb zorrar (whose authenticity I have been unable to verify), allegedly of onomatopoeic origin."
