The author mentions difficulties with locating the full text of some papers. This seems like a good time to point out that you can take some DOI URLs, such as

The author mentions difficulties with locating the full text of some papers. This seems like a good time to point out that you can take some DOI URLs, such as http://dx.doi.org/10.1145/2424321.2424336 http://dx.doi.org/10.1145/2424321.2424336 , and turn them into freely-accessible DOAI URLs, such as http://doai.io/10.1145/2424321.2424336 http://doai.io/10.1145/2424321.2424336 . Also, see https://www.reddit.com/r/scholar https://www.reddit.com/r/scholar .