ISBN 978-1405332965. ↑ "Primula veris – Online Atlas of the British and Irish Flora". brc.ac.uk. ↑ "Cowslip – Primula veris". naturespot.org.uk. ↑ [dead link] ↑ "RHS Plant Selector – Primula veris". Retrieved 15 April 2020. ↑ "AGM Plants – Ornamental" (PDF). Royal Horticultural Society.