SELECT lastName, firstName FROM Consultants C, Consultants_Projects CP, Projects P, Clients_Projects CP1, Clients C1
WHERE CP.serialNumber = C.serialNumber
AND P.projectID = CP.projectID
AND CP1.projectID = P.projectID
AND C1.referenceNumber = CP1.referenceNumber
AND C.title = Practitioner
AND C1.clientSector = PUBLIC;