David Dobson has written several books on Scots abroad extracting the data from bona fide records. They are therefore quite useful. The one on heirs is probably info taken from Retours and Services of Heirs and perhaps testaments. In any case his books are very commonly found in any library pretending to have a genealogical section so they are not difficult to find. Try interlibrary loan if you are not close to a good one. Allan Gray