A sua pesquisa - ((communications convention) or (communication collections)) users dimensioning databases under - não corresponde a nenhum registo.

Talvez deva tentar algumas variações de ortografia:
communications convention » communications connections, communication connection, communication conversation
communication collections » communication applications, communication cohesion, communication foundations
dimensioning databases » dimensional databases, designing databases, dimensional database
users dimensioning » systems dimensioning, user dimension, users designing

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