Helpful links for Classic Mac OS material
Jaedworks is a great resource for HyperCard related matters
Jaedworks House of HyperCardThe HyperCard Center contains descriptions of most HyperTalk functions organized in a modern way
The HyperCard CenterHyperCard.org has lots of interesting HyperCard info
HyperCard.orgThe HyperCard Twitter...? That exists I guess
HyperCard Twitter AccountMISC
Rebecca Bettencourt: Definitive Guide to the HyperCard Stack File Format
Library of Congress Page on HyperCard