Go to http://dogbert.abebooks.com/servlet/SearchResults?bx=on&sts=t&ds=30&bi=0&kn=Scots+AND+language&sortby=2 and scroll down to numbers 16 (Scottish English, English Scottish) and
17 (The Pocket Scots Dictionary).
Then, on to
19 (Pocket Guide to Scottish Words),
21 (The Pride O’ Scotland. A Scots-English Parallel of Matthew , Mark, Luke and John),
27 (The Old Scots Tounge : Scottish Words and their Meanings – ‘10,000 Scottish Words and their meanings.’ A useful little book but please note the typeface is very small and a magnifying glass may be required),
30 (Scottish Words and Phrases), and
49 (The Scots Dialect Dictionary --on the second page).
There are several pages of stuff. Many entries appear more than once–different prices from different sellers. Pay attention to the condition, which is usually noted. American Book Exchange is one of my major sources for academic texts. A used text book can cost a quarter of what it would sell for new, and they can be in really good condition.
On searching for “lallans” (thanks to DCrom) as a keyword, I found http://dogbert.abebooks.com/servlet/SearchResults?kn=lallans&bsi=30 and
number 36 (THE SCOTTISH TONGUE, a Series of Lectures on the Vernacular Language of Lowland Scotland),
89 (and 94 & 95) (LALLANS, A SELECTION OF SCOTS WORDS ARRANGED AS AN ENGLISH-SCOTTISH DICTIONARY WITH PRONUNCIATION AND EXAMPLES and
98 (Scots : The Mither Tongue).
That should get you started. If I recall correctly (what are the chances?) from discussions on sci.lang, “Scottish English” and “Scots” are quite different. “Scots” is not just a variety of English.
A quick Google found http://encyclopedia.laborlawtalk.com/Scots_language saying:
Scots (or Lallans, meaning ‘Lowlands’), properly Lowland Scots, is a Germanic language used in Lowland Scotland, as well as parts of Northern Ireland and border areas of the Republic of Ireland, where it is known in official circles as Ulster Scots or Ullans but by speakers simply as “Scotch” or “Scots”. On the whole, Lowland Scots descends from the Northumbrian form of Anglo-Saxon, albeit with influence from Norse via the Vikings, Dutch and Low Saxon through trade with, and immigration from, the low countries, and Romance via ecclesiastical and legal Latin, Anglo-Norman and later Parisian French owing to the Auld Alliance. Lowland Scots also has loan words resulting from contact with Scottish Gaelic, a Celtic language distinct from Lowland Scots still spoken by some in the Highlands and islands to the west. Loan words from Scottish Gaelic are mainly for geographical and cultural features, such as clan and loch (‘lake’). Like any living language, Lowland Scots has changed to some extent over the years, though it has arguably remained closer to its Anglo-Saxon roots than English. Many Lowland Scots words have become part of English: flit, ‘to move home’, greed, eerie, cuddle, clan, stob, ‘a post’.