The last posting on a 1904 article in the Boston Evening Transcript (here) concerning the state of Christianity in Siam noted the importance of the religious and secular press as a source for the study of the church in Siam up to the 1920s. That thought inspired me to see if the North Carolina Presbyterian is available online, and it turns out that it is. The North Carolina Presbyterian was a nineteenth-century publication that is a key source for the study of the Laos Mission from it inception in 1867 into the 1890s. The Rev. Dr. Daniel McGilvary was from North Carolina and sent numerous letters and quite a few articles back to the publication over the years, which thus contains data available nowhere else about the mission, its churches, and its personnel. The paper is also an important source for the study of northern Thai history generally.
It turns out that almost all of the issues of the North Carolina Presbyterian are available online at the Internet Archive. They are not listed there in order, however, and I have taken the liberty of listing them chronologically beginning with the first available year 1861 until the paper ceased publication in 1898. Linked to An English-Language Bibliography of Materials
Related to Christianity in Thailand, you can access the list (here).