==Secondary Classifications==
{| class="wikitable" style="text-align: left"
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|A = Arms, general||HEA = History, Ancient
|-
|AT = Arms, Tartans||HEAR = History, Arthurian
|-
|AV = Arms, Vexillology||HEC = History, Crusades
|-
|C = Chivalry||HED = History, Age of Discovery
|-
|CA = Chivalry, Arms & Armor||HED = History, Age of Discovery
|-
|CI = Chivalric Insignia||HEM = History, Medieval
|-
|CM = Chivalry, Militaria||HER = History, Renaissance
|-
|CO = Orders of Chivalry||HF = Faith, Religion, Myth
|-
|E = Encyclopediæ||HFC = Faith, Christian
|-
|F = Fiction||HFD = Faith, Druidic
|-
|G = Genealogy||HFI = Faith, Islamic
|-
|GF = Genealogy, Family||HFJ = Faith, Judaic
|-
|GFC = Genealogy, Family, Collective||HFM = Mythology
|-
|GFN = Genealogy, Family, by Name||HG = Geography (not including maps)
|-
|GG = Genetic Genealogy||HN = History, National [1]
|-
|GI = Genealogical Indices||HP = History, Peoples [3]
|-
|GM = Genealogical Magazines (general)||HR = History, Regions (multiple nations)
|-
|GN = Genealogy, National [1]||M = Maps, Atlases, Gazetteers
|-
|GP = Genealogy, Peoples [4]||N = Numismatics
|-
|GR = Genealogy, Regional||P = Philatelics
|-
|GS = Genealogy, State [2]||R = Royalty & Nobility
|-
|H = History||RB = Biography [4]
|-
|HAN = History, Anthropology||RBC = Biography, Collective
|-
|HAR = History, Archaeology||RH = Royal & Noble Houses
|-
|HC = Castles, Architecture||W = Who's Who
|-
|HE = History, Eras||
|}
{| class="wikitable" style="text-align: left"