siblings of Efficient xx

half siblings paternal

horse Stuyvesant xx (Thoroughbred, 1949, from Princequillo xx)

Stuyvesant xx

broodmare Ruling Princess xx (Thoroughbred, 1963, from Princequillo xx)

Ruling Princess xx

stallion Prince Arthur xx (Thoroughbred, 1954, from Princequillo xx)

Prince Arthur xx

horse Seventh Sun xx (Thoroughbred, 1949, from Princequillo xx)

Seventh Sun xx

broodmare Royal Bride xx (Thoroughbred, 1952, from Princequillo xx)

Royal Bride xx

broodmare Monarchy xx (Thoroughbred, 1957, from Princequillo xx)

Monarchy xx

broodmare Dungaree xx (Thoroughbred, 1956, from Princequillo xx)

Dungaree xx

broodmare Czarina xx (Thoroughbred, 1956, from Princequillo xx)

Czarina xx

broodmare Lady O'War xx (Thoroughbred, 1956, from Princequillo xx)

Lady O'War xx

broodmare Beesandbirds xx (Thoroughbred, 1962, from Princequillo xx)

Beesandbirds xx

broodmare Queens Full xx (Thoroughbred, 1955, from Princequillo xx)

Queens Full xx

broodmare Equilla xx (Thoroughbred, 1950, from Princequillo xx)

Equilla xx