could reference
Regular verb: reference - referenced- referenced

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could reference
you could reference
she could reference
we could reference
you could reference
they could reference 	I could be referencing
you could be referencing
she could be referencing
we could be referencing
you could be referencing
they could be referencing	I could have referenced
you could have referenced
she could have referenced
we could have referenced
you could have referenced
they could have referenced	I could have been referencing
you could have been referencing
she could have been referencing
we could have been referencing
you could have been referencing
they could have been referencing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't reference
you couldn't reference
she couldn't reference
we couldn't reference
you couldn't reference
they couldn't reference 	I couldn't be referencing
you couldn't be referencing
she couldn't be referencing
we couldn't be referencing
you couldn't be referencing
they couldn't be referencing	I couldn't have referenced
you couldn't have referenced
she couldn't have referenced
we couldn't have referenced
you couldn't have referenced
they couldn't have referenced	I couldn't have been referencing
you couldn't have been referencing
she couldn't have been referencing
we couldn't have been referencing
you couldn't have been referencing
they couldn't have been referencing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I reference?
could you reference?
could she reference?
could we reference?
could you reference?
could they reference? 	could I be referencing?
could you be referencing?
could she be referencing?
could we be referencing?
could you be referencing?
could they be referencing? 	could I have referenced?
could you have referenced?
could she have referenced?
could we have referenced?
could you have referenced?
could they have referenced? 	could I have been referencing?
could you have been referencing?
could she have been referencing?
could we have been referencing?
could you have been referencing?
could they have been referencing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I reference?
couldn't you reference?
couldn't she reference?
couldn't we reference?
couldn't you reference?
couldn't they reference? 	couldn't I be referencing?
couldn't you be referencing?
couldn't she be referencing?
couldn't we be referencing?
couldn't you be referencing?
couldn't they be referencing? 	couldn't I have referenced?
couldn't you have referenced?
couldn't she have referenced?
couldn't we have referenced?
couldn't you have referenced?
couldn't they have referenced? 	couldn't I have been referencing?
couldn't you have been referencing?
couldn't she have been referencing?
couldn't we have been referencing?
couldn't you have been referencing?
couldn't they have been referencing?