This and similar questions should be in the 'Tartan' thread; however, the answer's still the same - Johnston in Weathered Colours.

There are many books and online databases of tartans but none holds every tartan, nor could it as there are new ones every week. Also, such resources cannot include all the colour ways and so one has to have a base knowledge. If in doubt this forum is undoubtedly the best public access resource because there's a lot of collective knowledge andit's free.