ante before
dito same as (with relation to something mentioned previously)
ibid. used to refer to the work cited in the preceding note
idem the same as something previously mentioned
ill. illustrated
ms handwritten
n.d. not dated
n.s. not signed
post after
s.n. no number
ALS autograph letter signed
ACS autograph card signed
APCS autograph postcard signed
TLS typed letter signed
TL typed letter unsigned
FdDPS Endowment Fund Philippe Smit
LNC The Lord’s New Church, Bryn Athyn, PA
Glencairn archives The Bryn Athyn Historic District Archives at Glencairn Museum
PMA Philadelphia Museum of Fine Arts
RKD Rijksbureau voor Kunsthistorische Documentatie (Netherlands Institute for Art History)