These may or may not be "must haves" but with regard to Port they are both interesting and informative and I'm glad I have them:Steven Kooij wrote: Any other books out there that are "must have's"?
The Factory House at Oporto ... John Delaforce, 1979, ISBN 0 903 432 17 X
Port ... George Robertson, 1978, ISBN 0 571 11923 I
The Wines of Portugal ... Jan Read, 1982, 1987, ISBN 0 571 15003 9
Port & Sherry ... Geo G sandeman Sons & Co Limited, 1955, second, revised edition 1964
Wine Dynasties of Europe ... Harry Eyres, 1990, ISBN 1 85291 088 7
Port ... a 19 page pamphlet "written in the hope that it may be of help to some of those Visitors to Wine Lodges in Villa Nova de Gaya (sic), and to Vineyards in the Port Wine District of the Douro, who are not in the Wine Trade." 1949, reprinted 1950, Tipografia Barbosa, Gaia. My copies are rubber ink-stamped "Taylor, Fladgate & Yeatman, Villa Nova de Gaya, Portugal.