I found a plethora of books at Google that have copious illustrations of costumes from various countries and periods that ought to be of interest for anybody designing Poser historical costumes. I was surprised to find that quite a few of these books are in color even though they're more than a century old. All of these books are downloadable in their entirety.

http://books.google.com/books?id=RoSBAAAAMAAJ  [color] English costume By Dion Clayton Calthrop
http://books.google.com/books?id=i1-BAAAAMAAJ  [color] Costume: fanciful, historical, and theatrical By Eliza Aria, Aria (Eliza Davis), Percy Anderson
http://books.google.com/books?id=VUYOAAAAQAAJ  [color] Aggiunte all'opera Il costume antico e moderno di tutti i popoli, cogli ... By Giulio Ferrario
http://books.google.com/books?id=lbxJAAAAIAAJ  [color] China: It's Costume, Arts, Manufacture By Breton (Jean Baptiste Joseph)
http://books.google.com/books?id=py8BAAAAQAAJ  [color] Notes on civil costume in England from the Conquest to the Regency. As ... By Lewis Wingfield
http://books.google.com/books?id=MUYOAAAAQAAJ  [color] Il costume antico e moderno o storia del governo, della milizia, della ... By Giulio Ferrario, Robustiano Gironi
http://books.google.com/books?id=lev9K0S4b6gC  [color] Costume de moyen áge d'après les manuscrits By Jacques Joseph van Beveren, Charles Dupressoir
http://books.google.com/books?id=xttAAAAAIAAJ  Two centuries of costume in America, MDCXX-MDCCCXX By Alice Morse Earle
http://books.google.com/books?id=R3IuAAAAYAAJ  History of British costume By James Robinson Planché
http://books.google.com/books?id=aQIFAAAAYAAJ  The illustrated toilet of fashion, or, Annals of costume, from the earliest ...
http://books.google.com/books?id=fw8tAAAAYAAJ  Le costume de la femme à travers les âges By Paris. Exposition Universelle, 1900. Palais du costume
http://books.google.com/books?id=JS4LAAAAIAAJ  British costume By James Robinson Planché
http://books.google.com/books?id=Zy4uAAAAYAAJ  Histoire du costume en France By Jules Étienne Joseph Quicherat
http://books.google.com/books?id=f419oz-NWDgC  Cyclopaedia of Costume Or Dictionary of Dress, Including Notices of ... By James Robinson Planché
http://books.google.com/books?id=Sjfhv4ZytooC  Costume in England By Frederick William Fairholt, Harold Arthur Lee-Dillon Dillon
http://books.google.com/books?id=_A0LAAAAIAAJ  Costume design and illustration By Ethel Traphagen
http://books.google.com/books?id=YO5CAAAAIAAJ  A manual of costume as illustrated by monumental brasses By Herbert
http://books.google.com/books?id=s9ADAAAAYAAJ  The Quaker By Amelia Mott Gummere
http://books.google.com/books?id=KPgUAAAAYAAJ  The book of costume: or, Annals of fashion, from the earliest period to the ... By Mary Margaret
http://books.google.com/books?id=FywLAAAAIAAJ  Chronicles of Fashion Vol 1 By Elizabeth Stone
http://books.google.com/books?id=G5wTAAAAYAAJ  Essai sur l'histoire du théâtre la mise en scène, le décor, le costume, l ... By Germain Bapst

The below link was the one that got me interested in seeing what I could find at Google Books (I found this link while searching for something else).

http://www.siue.edu/COSTUMES/history.html

Wow what a treasure. Thanks for sharing.

Here is one I found :)

books.google.com/books

Thank you!!

Laurie

The Internet is the gifit that just keeps giving. Thanks for the treasure. 

I found another site. It contains the archives that Microsoft was scanning and gave up on.

http://www.archive.org/details/britishcostumedu00ashduoft  British costume during 19 centuries, civil and ecclesiastical (1910)
http://www.archive.org/details/dressinsigniawor00greauoft  Dress and insignia worn at His Majesty's court, issued with the authority of the lord chamberlain (1921)
http://www.archive.org/details/englishcostumefr00clin  English costume from prehistoric times to the end of the eighteenth century (1910)
http://www.archive.org/details/englishinmiddlea00hodguoft  The English in the Middle Ages : from the Norman usurpation to the days of the Stuarts. Their mode of life, dress, arms, occupations and amusements, as illustrated by the mediaeval remains in the British Museum (1885)
http://www.archive.org/details/japanesecostume12guns  Japanese costume (1923)

http://www.archive.org/details/chatsoncostume00rhea  Chats on costume (1906)
http://www.archive.org/details/costumeofancient02hopeuoft  The costume of the ancients (1875)
http://www.archive.org/details/lecostumecivilin00pitouoft  Le costume civil in France du XIIIe au XIXe siècle
http://www.archive.org/details/histoireducostum00heuzuoft  Histoire du costume antique d'après des études sur le modèle vivant - Heuzey, Léon Alexandre, 1831-1922
http://www.archive.org/details/bookcostumefrom00rankgoog  The Book of Costume: From the Earliest Period to the Present Time - Mary Margaret (Stanley) Egerton Wilton
http://www.archive.org/details/costumeinengland01fairuoft  Costume in England : a history of dress to the end of the eighteenth century Vol 1 (1896)
http://www.archive.org/details/costumeinengland02fairuoft  Costume in England : a history of dress to the end of the eighteenth century Vol 2 (1896)
http://www.archive.org/details/aggiunteallopera03ferr  [color] Aggiunte all'opera Il costume antico e moderno di tutti i popoli, cogli analoghi disegni (1833)
http://www.archive.org/details/borneoindianarch00marruoft  Borneo and the Indian archipelago. With drawings of costume and scenery (1948)
http://www.archive.org/details/aggiunteallopera01ferr  Aggiunte all'opera Il costume antico e moderno di tutti i popoli, cogli analoghi disegni (Volume 1) - Ferrario, Giulio, 1767-1847
http://www.archive.org/details/aggiunteallopera02ferr  Aggiunte all'opera Il costume antico e moderno di tutti i popoli, cogli analoghi disegni (Volume 2) - Ferrario, Giulio, 1767-1847

English costume By Dion Clayton Calthrop
http://www.archive.org/details/englishcostume00calt  "" Vol 1 (better scans)
http://www.archive.org/details/englishcostume02calt  "" Vol 2
http://www.archive.org/details/englishcostume03calt  "" Vol 3
http://www.archive.org/details/englishcostume04calt  "" Vol 4