1          Preface

5          Chapter I        The Yang-Mills Lagrangian

18        Chapter II       Description, of instantons

34        Chapter III      The Penrose twistor space

42        Chapter IV     Holomorphic bundles

56        Chapter V      The Horrocks construction

64        Chapter VI     Linear field equations in a Yang-Mills background

82        Chapter VII    Theorems on algebraic bundles

94        Chapter VIII   Open problems

97        References