I haven't personally read Mr. Borrow's works as of yet, but I think the depth of his writing is spoken to by the number of citings his writings continually receive in newer books on Gypsies. Aside from the books listed above, Angus Fraser's book "The Gypsies" was very well written. If I remember correctly I particularly liked his linguistic explanations. There are many sources available for Gypsy research if you know where to look. There is a company in the UK called Cottage Books at Gelsmoor, Coleorton, Leicestershire, LE67 8HR that has a 32 page catalogue just on printed books and articles about Gypsies. The Journal of The Gypsy Lore Society is certainly one of the first places to visit: www.gypsyloresociety.org