Variation of Hodge Structure: The Singularities of the Period Mapping. Wilfried Schmid (1973) Inventiones mathematicae
Variation of mixed Hodge structure. I. Joseph Steenbrink, Steven Zucker (1985) Inventiones mathematicae
Variational Torelli implies generic Torelli. L. Tu, D. Cox, R. Donagi (1987) Inventiones mathematicae