This gives a good selection of Scottish family histories some more reliable than others when good primary source records are included. Another good source of Scottish reference books is archive.org which also has a good number of Scottish Record Society books pre -1920. That source also has books on charters of many Scottish Abbeys, the Register of the Great Seal (exept Vol.i but does have Robertson Index of Charters ), Farquharson's Genealogical Connections and other useful source books.
