Terry traveled to Celtic lands in 1997, visiting the northern area of County Clare and the western islands of Scotland, where he attended a 10-day training in Celtic Shamanism. He will bring his experiences and family history to the performance of these stories and songs.
It is unas libretas. Unas is femenine and plural indefinite article, and it match with libretas. You do not have more options @Crissy15 in this case. @Crissy15 if you say las libretas you are using the femenine and plural definite article las. if you say unas libretas you are using the femenine and plural indefinite article unas. Crissy15.
(2010, October 13). Cite in text the first few words of the reference list entry (usually the title) and the year. Use double quotation marks around the title or abbreviated title.: (All 33 Chile Miners, 2010). Note: Use the full title of the web page if it is short for the parenthetical citation. Articles found on the web, like the example above, are not italicized in the reference entry and are not italicized but enclosed in quotations in the in-text citation, just like a newspaper or magazine article.