Ama ni Parda wrote Umpama Batak dohot Lapatanna and published it in 1976.
I met Ama ni Parda during my first period of fieldwork in 1979 - 1980 and purchased the book from him then. He was concerned about the loss of Batak culture and he had his own printing press. He was a dedicated, passionate man.
In 2015 I met Roy Andry Siregar, a student at STT in Pematang Siantar. He is writing a paper about the cultural significance of Batak umpama and umpasa (sayings) but he is troubled by a lack of resources. I promised that I would go through my books to try to find something that might be of use to him. I have selected Ama ni Parda's work because it includes the meanings of the umpama.
This medium is clumsy for distributing the book to those who want to print it out but at least it is available. We need a kind of WikiBatakologia for Batak literature.