The National Library's highlight of the month of July is the play Tengdamamma (Mother-in-law), by Kristín Sigfúsdóttir, thatwas published as a book in 1923 due to its popularity. It was written in 1920 and staged a year later in many places around Eyjafjörður and in Akureyri, as well as in Iðnó (Reykjavík Theatre Company) in 1923. It was one of the few plays that were performed on stage at that time by an Icelandic woman. The play was then performed on radio in 1977 in connection with Kristín's centenary.

Kristín was born on July 13, 1876 at Helgastadir in Saurbæjarhreppur parish in Eyjafjörður. Mother-in-law was her first work to be published as a book, it was followed by two other plays, although many more were staged, along with one collection of short stories and two novels. She married Pálmi Jóhannesson in 1901 and they had six children together. When Kristín turned forty and all her children had come of age she could put more time into her writing. She was then around forty years old. They lived in a farm in Eyjafjörður but the family moved to Akureyri in 1930 and lived there most of the time at the house Sigurhæðir. Kristín passed away in 1953.

Kristín started composing verses at a young age and wrote several poems throughout her life. She burned quite a few of her manuscripts from an early age. However, some of them were preserved and are now kept in her private archive at Kvennasögusafn (the Women's History Archives). It was handed over by Kristín's daughter and foster daughter, Guðrún Pálmadóttir and Lilja Sigurðardóttir, together with Sigrún Klara Hannesdóttir (later National Librarian) in 1994. 

A chapter from Tengdamamma was published in the journal Embla in 1946 and can be viewed here.