Here is an example of two in-text citations, and the references. It must be an issue with the fact that et al authors are different. Can this be overridden?
(Bonow et al., 2006a; Bonow et al., 2006b; Bonow et al., 2007; Green et al., 2011)
(Lane et al., 2006, 2010)
BONOW, J. M., JAPSEN, P., LIDMAR-BERGSTRÖM, K., CHALMERS, J. A. & PEDERSEN, A. K. 2006a. Cenozoic uplift of Nuussuaq and Disko, West Greenland—elevated erosion surfaces as uplift markers of a passive margin. Geomorphology, 80 , 325-337.
BONOW, J. M., LIDMAR-BERGSTROM, K. & JAPSEN, P. 2006b. Palaeosurfaces in central West Greenland as reference for identification of tectonic movements and estimation of erosion. Global and Planetary Change, 50 , 21.
BONOW, J. M., LIDMAR-BERGSTRÖM, K., JAPSEN, P., CHALMERS, J. A. & GREEN, P. F. 2007. Elevated erosion surfaces in central West Greenland and southern Norway: their significance in integrated studies of passive margin development. NORWEGIAN JOURNAL OF GEOLOGY, 87 , 10.
GREEN, P. F., JAPSEN, P., CHALMERS, J. A. & BONOW, J. M. 2011. Thermochronology, erosion surfaces and missing section in West Greenland. Journal of the Geological Society, 168 , 817-830.
LANE, T. P., REA, B. & ROBERTS, D. H. 2006. l;j’.
LANE, T. P., REA, B. & ROBERTS, D. H. 2010. kjjl.